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All questions of Indices for SSS 1 Exam

The ratio between the LCM and HCF of 5,15, 20 is:
  • a)
    9 : 1
  • b)
    4 : 3
  • c)
    11 : 1
  • d)
    12 : 1
Correct answer is option 'D'. Can you explain this answer?

Ananya Das answered
Factors are following:
5 = 5 x 1
15 = 5 x 3
20 = 2 x 2 x 5
LCM = 5 x 3 x 2 x 2 = 60
HCF = 5
Ratio = LCM/HCF = 60/5 = 12/1 = 12:1
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√7 is
  • a)
    an integer
  • b)
    an irrational number 
  • c)
    a rational number 
  • d)
    none of these
Correct answer is option 'B'. Can you explain this answer?

Lets assume that √7 is rational number. ie √7=p/q.
suppose p/q have common factor then
we divide by the common factor to get √7 = a/b were a and b are co-prime number.
that is a and b have no common factor.
√7 =a/b co- prime number
√7= a/b
a=√7b
squaring
a^2=7b^2 ....1
a� is divisible by 7
a=7c
substituting values in 1
(7c)^2=7b^2
49c^2=7b^2
7c^2=b^2
b^2=7c^2
b^2 is divisible by 7
that is a and b have atleast one common factor 7. This is contridite to the fact that a and b have no common factor.This is happen because of our wrong assumption.
√7 is irrational.

Find the greatest number of 5 digits, that will give us remainder of 5, when divided by 8 and 9 respectively.
  • a)
    99921
  • b)
    99931
  • c)
    99941
  • d)
    99951
Correct answer is option 'C'. Can you explain this answer?

Avinash Patel answered
Greatest 5-Digit number = 99999
LCM of 8 and 9,
8 = 2 × 2 × 2
9 = 3 × 3
LCM = 2 × 2 × 2 × 3 × 3 = 72
Now, dividing 99999 by 72, we get
Quotient = 1388
Remainder = 63
So, the greatest 5-digit number divisible by 8 and 9 = 99999 - 63 = 99936
Required number = 99936 + 5 = 99941

How many whole numbers are there between 42 and 62 ?
    • a)
      20
    • b)
      21
    • c)
      23
    • d)
      none of the above
    Correct answer is option 'D'. Can you explain this answer?

    Aarav murthy answered

    Explanation:

    There are infinite whole numbers between two given whole numbers. In the case of the question, the range is between 42 and 62. Therefore, there are infinitely many whole numbers between 42 and 62.

    Here are some key points to consider:

    Key Points:
    - Whole numbers are the set of numbers that include all positive integers from 0, 1, 2, 3, ...
    - The numbers between 42 and 62 are inclusive of both 42 and 62.
    - Therefore, the count of whole numbers between 42 and 62 is infinite.

    It is important to note that the concept of whole numbers does not have a specific endpoint, as they continue indefinitely in both directions on the number line. Thus, the correct answer is option 'D' - none of the above.

    Which of the following rational numbers have a terminating decimal expansion?
    • a)
      125/441
    • b)
      77/210
    • c)
      15/1600
    • d)
    Correct answer is option 'C'. Can you explain this answer?

    Krishna Iyer answered

    The denominator 26 x 52 is of the form 2m x 5n, where m and n are non-negative integers. Hence, it is a terminating decimal expansion.

    The largest number which divides 245 and 1029 leaving remainder 5 in each case is
    • a)
      4
    • b)
      8
    • c)
      12
    • d)
      16
    Correct answer is option 'D'. Can you explain this answer?

    Krishna Iyer answered
    When 245 and 1029 are divided by the required number then there is left 5 as remainder. It means that 245 - 5 = 240 and 1029 - 5 = 1024 will be completely divisible by the required number.
    Now we determine the HCF of 240 and 1024 by Euclid's Algorithm.
    1024 = 240 x 4 + 64
    240 = 64 x 3 + 48
    64 = 48 x 1 + 16
    48 = 16 x 3 + 0
    Since remainder comes zero with last divisor 16,
    required number = 16

    The decimal expansion of number 
    • a)
      terminating decimal
    • b)
      non-terminating repeating decimal
    • c)
      non-terminating and non-repeating decimal
    • d)
      none of these
    Correct answer is option 'A'. Can you explain this answer?

    Naina Sharma answered
    A number with terminal decimal expansions have the denominator  in the form,
    2m 5where m & n ∈ W.
    The number 
    Which the denominator is in the form,
     with m = 2 , n = 3.
    Hence, it has terminal decimal expansion.

    The relationship between HCF and LCM of two natural numbers is
    • a)
      HCF × LCM = Product of two natural numbers
    • b)
      HCF × LCM = Sum of two natural numbers
    • c)
      HCF × LCM = Difference of two natural numbers
    • d)
      None of these
    Correct answer is option 'A'. Can you explain this answer?

    Ananya Das answered
    The product of LCM and HCF of any two given natural numbers is equivalent to the product of the given numbers.
    LCM × HCF = Product of the Numbers
    Suppose A and B are two numbers, then.
    LCM (A & B) × HCF (A & B) = A × B
    Example: Prove that: LCM (9 & 12) × HCF (9 & 12) = Product of 9 and 12.
    ->LCM and HCF of 9 and 12:
    9 = 3 × 3 = 3²
    12 = 2 × 2 × 3 = 2² × 3
    LCM of 9 and 12 = 2² × 3² = 4 × 9 = 36
    HCF of 9 and 12 = 3
    LCM (9 & 12) × HCF (9 & 12) = 36 × 3 = 108
    Product of 9 and 12 = 9 × 12 = 108
    Hence, LCM (9 & 12) × HCF (9 & 12) = 108 = 9 × 12

    The product of two consecutive integers is divisible by
    • a)
      2
    • b)
      3
    • c)
      5
    • d)
      7
    Correct answer is option 'A'. Can you explain this answer?

    Raghav Bansal answered
    As the case is of 2 consecutive integers, one will be odd and the other one even,
    ⇒ Their product will always be even i.e. it will always be divisible by an even no., i.e. 2, here.

    What is the number x The LCM of x and 18 is 36. The HCF of x and 18 is 2.
    • a)
      2
    • b)
      3
    • c)
      1
    • d)
      4
    Correct answer is option 'D'. Can you explain this answer?

    Anjana Khatri answered
    LCM * HCF = product of the integers 
    36 * 2 = 18 + p
    36 * 2 / 18 = p 
    72 / 18 = p
    Therefore p = 4 
    Hope you liked my answer. If so mark me as brainliest.

    Every positive odd integer is of the form 2q + 1, where ‘q’ is some
    • a)
      whole number
    • b)
      natural number
    • c)
      integer
    • d)
      none of these
    Correct answer is 'C'. Can you explain this answer?

    Rohan Kapoor answered
    Let a be any positive integer and b = 2.

    Applying Euclid’s algorithm, we have:

    a = 2q + r, for some integer q ≥ 0, and 0 ≤ r < 2

    a = 2q or 2q + 1

    If a = 2q, then a is an even integer.

    Now, a positive integer can either be even or odd. Thus, any positive odd integer is of the form 2q + 1.

    The HCF of 2472, 1284 and a third number N is 12. If their LCM is 23 x 32 x 5 x 103 x 107, then the number N is :
    • a)
      22 x 32 x 7
    • b)
      22 x 33 x 103
    • c)
      22 x 32 x 5
    • d)
      24 x 32 x 11
    Correct answer is option 'C'. Can you explain this answer?

    Given that, LCM (2472, 1284, and n) is 2× 3× 5 × 103 × 107
    Let us express the numbers 2472, and 1284 as a product of prime numbers.
    2472 = 2 × 2 × 2 × 3 × 103  (23 × 3 × 103)
    1284 = 2 × 2 × 3 × 107 (2× 3 × 107)
    HCF (2472, 1284)=  2 × 2 × 3 (2× 3)
    'n' should also have one of the factors as HCF, and another factor as the missing element of other numbers from the LCM (i.e., 3 × 5)
    Therefore,
    n =  22 × 3 × (3 × 5)
    n = 22 × 32 × 5
    n = 4 × 9 × 5
    n = 180
    Therefore, if the HCF of 2472 and 1284 and a third number 'n' is 12 and if their LCM is 23 × 3× 5 × 103 × 107, then the number 'n' is 180 (22 × 32 × 5)

    The HCF of 867 and 255 is
    • a)
      51
    • b)
      25
    • c)
      55
    • d)
      35
    Correct answer is option 'A'. Can you explain this answer?

    Amit Sharma answered
    As, 867=255 × 3 +102
    255 = 102 × 2 + 51
    102 = 51 × 2 + 0
    So, HCF (867,255) = 51

    Any ____________ is of the form 4q + 1 or 4q + 3 for some integer ‘q’.
    • a)
      composite number
    • b)
      positive odd integer
    • c)
      prime number
    • d)
      positive even integer
    Correct answer is option 'B'. Can you explain this answer?

    Neha Patel answered
    Let a be any positive integer 
    by EDL  a = bq +r 
    0 ≤ r < b
    possible remainders are 0, 1, 2 , 3 
     this shows that a can be in the form of 4q, 4q+1, 4q+2, 4q+3 q is quotient 
    as a is odd a  can't be the form of 4q or 4q+2 as they are even
    so a ill be in the form of 4q + 1 or 4q+3 
    hence proved

    The HCF of two consecutive even numbers is
    • a)
      1
    • b)
      2
    • c)
      0
    • d)
      3
    Correct answer is 'B'. Can you explain this answer?

    Rajiv Gupta answered
    Let's take two consecutive even numbers i.e, 2x and 2x+2.

    Method 1 : Factorisation

    Now factor both numbers

    2 * x and 2 * (x+1). Therefore, the only common factor we get here is one and only 2, which turns out to be HCF itself.

    Hence, HCF of two even consecutive number is 2.

    Example take 10 and 12 or 4 and 6 HCF always turns out to be 2 as

    10=2*5 and 12=2*6


    Method 2:

    If we calculate through simple division process. Let's say two consecutive even numbers are n and n+2.

    If n+2 is divided by n, we get the remainder as 2.

    And n is divisible by 2 as it is an even number.

    Hence, HCF is 2.

    If 112 = q×6+r, then the possible values of r are:
    • A:
      2, 3, 5
    • B:
      0, 1, 2, 3, 4, 5
    • C:
      1, 2, 3, 4
    • D:
      0, 1, 2, 3
    The answer is b.

    Ananya Das answered
    For the relation x = qy+r, 0 ⩽ r < y So, here r lies between 0 ⩽ r < 6. Hence r = 0, 1, 2, 3, 4, 5

    n2 - 1 is divisible by 8 if n is
    • a)
      An integer
    • b)
      A natural number
    • c)
      An odd integer
    • d)
      An even integer
    Correct answer is option 'C'. Can you explain this answer?

    Pooja Shah answered
    Option A: If n is integer similarly n²- 1 is not divisible by 8.
    Option B: If n is a natural number then it is not possible for n=1,2.
    Option C: If n is odd the possible for n is 3,5,7...
    Option D: If n is even then it is not possible for n=2.
    Thus, the option C is correct.

    The least perfect square number which is divisible by 3, 4, 5, 6 and 8 is
    • a)
      900
    • b)
      1200
    • c)
      2500
    • d)
      3600
    Correct answer is option 'D'. Can you explain this answer?

    Naina Sharma answered
    L.C.M. of 3, 4, 5, 6, 8 = 2 × 2 × 2 × 3 × 5 = 120 
    Pair of 2, 3 and 5 is not completed.
    To make it a perfect square, the number should be multiplied by 2, 3, 5.
    Required number = 120 x 2 x 3 x 5 = 3600.

    Two natural numbers whose difference is 66 and the least common multiple is 360, are:
    • a)
      120 and 54
    • b)
      90 and 24
    • c)
      180 and 114
    • d)
      130 and 64
    Correct answer is option 'B'. Can you explain this answer?

    Aditya Shah answered
    Let the two numbers be x and x+66.
    Since, the LCM is 360, there must be 5,2 and 3 as the prime factors of the two numbers.
    So, one pair is 24 & 90, because 90−24=66.
    Also, 24=2×2×2×3
    90=2×3×3×5
    ∴ LCM=2×2×2×3×3×5=360.
    So, the numbers are 24 and 90.

    Can you explain the answer of this question below:
    The product of two numbers is -20/9. If one of the numbers is 4, find the other. 
    • A:
      –5/9
    • B:
      3/11 
    • C:
      12/39
    • D:
      –9/11
    The answer is a.

    Ananya Das answered
    We have two numbers such that their product is equal to -20/9.
    So we have x*y=-20/9
    One no. is given 4, so
    x*4=-20/9
    x=-20/9 = 4
    x=-20/9 x 1/4=-5/9

    If two positive integers a and b are written as a and x3y2 and b = xy3, where x, y are prime numbers, then HCF(a, b) is
    • a)
      xy
    • b)
      xy2
    • c)
      x3y3
    • d)
      x2y2
    Correct answer is option 'C'. Can you explain this answer?

    Gaurav Kumar answered
    Here, a = x3y2 and b = xy3.
    ⇒ a = x * x * x * y * y and b = xy * y * y
    ∴ LCM(a, b) = x * y * y = x3 * y3 = x3y3
    LCM = x3y3

    The multiplicative inverse of zero is
    • a)
      is 1
    • b)
      is 0
    • c)
      is 1/0
    • d)
      does not exist
    Correct answer is option 'B'. Can you explain this answer?

    Krishna Iyer answered
    Some rules associated with Multiplicative Inverse are discussed in following ways :- 
    Rule 1 = If product of two Fractional Numbers is equal to 1, then each of the Fractional Numbers is the Multiplicative Inverse of other. 
    Rule 2 = If the product of a Fractional Number and a Whole Number is equal to 1, then each is the Multiplicative Inverse of other. 
    Rule 3 = Multiplicative Inverse of 1 is also 1. 
    Rule 4 = Multiplicative Inverse of 0 (zero) does not exists 

    The answer of 1⁄3 x 8² + 2² is
    • a)
      7.1667
    • b)
      6.1667
    • c)
      4.1667
    • d)
      5.1667
    Correct answer is option 'C'. Can you explain this answer?

    Raghav Bansal answered
     Since, 5 and 8 are the remainders of 70 and 125, respectively. Thus, after subtracting these remainders from the numbers, we have the numbers 65 = (70-5),
    117 = (125 – 8), which is divisible by the required number.
    Now, required number = HCF of 65,117                                     [for the largest number]
    For this, 117 = 65 × 1 + 52 [∵ dividend = divisior × quotient + remainder]
    ⇒ 65 = 52 × 1 + 13
    ⇒ 52 = 13 × 4 + 0
    ∴ HCF = 13 
    Hence, 13 is the largest number which divides 70 and 125, leaving remainders 5 and 8.

    The largest number which divides 70 and 125 leaving remainders 5 and 8 respectively is 
    • a)
      13
    • b)
      65
    • c)
      875
    • d)
      1750
    Correct answer is option 'A'. Can you explain this answer?

    Krishna Iyer answered
    The largest number by which x , y
    divisible and gives the remainder a ,
    and b is
    the HCF of ( x - a ) and ( y - b)
    According to the given problem ,
    The largest number which divides
    70 and 125 leaving remainders 5 and
    8 respectively are
    HCF of ( 70 - 5 ) = 65 and
    ( 125 - 8 ) = 117
    65 = 5 × 13
    117 = 3 × 3 × 13
    HCF ( 65 , 117 ) = 13
    Required number is 13.

    Which of the following numbers has terminating decimal expansion?
    • a)
      3/11
    • b)
      3/5
    • c)
      5/3
    • d)
      3/7
    Correct answer is option 'B'. Can you explain this answer?

    Arun Sharma answered
    3/5 has terminal decimal expansion because terminal decimal expansion should have the denominator 2 or 5 only.

    Every positive even integer is of the form ____ for some integer ‘q’.
    • a)
      2q
    • b)
      2q – 1
    • c)
      2q + 1
    • d)
      none of these
    Correct answer is option 'A'. Can you explain this answer?

    Let a be any positive integer and b = 2
    Then by applying Euclid’s Division
    Lemma, we have, a = 2q + r where 0 ⩽ r < 2 r = 0 or 1
    Therefore, a = 2q or 2q+1 
    Therefore, it is clear that a = 2q i.e., 
    a is an even integer in the form of 2q

    The HCF and LCM of two numbers is 9 and 459 respectively. If one of the number is 27, then the other number is
    • a)
      459
    • b)
      153
    • c)
      135
    • d)
      150
    Correct answer is option 'B'. Can you explain this answer?

    Girisha reddy answered
    Using the result, HCF * LCM = Product of two natural numbers ⇒ the other number =  product of two no. = LCM *HCF
    Let unknown no. = X
    >> X * 27 = 9*459
    X = 9*459/27
    X = 153

    So, option B is the correct answer. 
    You can study all the concepts of mathematics Class 10 by going through the link:

    If A = 2n + 13, B = n + 7, where n is a natural number, then HCF of A and B is:
    • a)
      2
    • b)
      1
    • c)
      3
    • d)
      4
    Correct answer is option 'B'. Can you explain this answer?

    Ritu Saxena answered
    Taking different values of n we find that A and B are coprime
    e.g. put n=1
    we get A= 2(1)+13=15
    B=1+7=8
    ∴ HCF = 1
     
    put n=2
    we get A= 2(2)+13=17
    B=2+7=9
    ∴ HCF = 1

    There are 576 boys and 448 girls in a school that are to be divided into equal sections of either boys or girls alone. The total number of sections thus formed are:
    • a)
      22
    • b)
      16
    • c)
      36
    • d)
      21
    Correct answer is option 'B'. Can you explain this answer?

    Gaurav Kumar answered
    The number 576 can be factorised as,
    576 = 2×2×2×2×2×2×3×3
    The number 448 can be factorised as,
    448=2×2×2×2×2×2×7
    Write the common factors of the given numbers.
    2×2×2×2×2×22×2×2×2×2×2
    Multiply the common factors to determine the highest common factor (HCF) of the given numbers.
    2×2×2×2×2×2 = 642×2×2×2×2×2 = 64
    Since the highest common factor (HCF) of the given numbers is 64, this implies that each section will have 64 number of students.
    Now, we need to find the number of sections formed.
    Let us first find the number of sections formed by the total number of boys by dividing 576 by 64.
    576/64 = 9
    Now, find the number of sections formed by the total number of girls by dividing 448 by 64.
    448/64=7
    Thus, the total number of sections formed will be 9+7=16
    Hence, option B is the correct answer.

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