Top JEE Doubts this Week

Charlie and Alan run a race between points A and B, 5 km apart. Charlie starts at 9 a.m. from A at a speed of 5 km/hr, reaches B, and returns to A at the same speed. Alan starts at 9:45 a.m. from A at a speed of 10 km/hr, reaches B and comes back to A at the same speed. At what time do Charlie and Alan first meet each other?
  • a)
    10 a.m.
  • b)
    10:20 a.m.
  • c)
    10:10 a.m
  • d)
    10:30 a.m.
Correct answer is option 'C'. Can you explain this answer?

Shraddha Mehta answered  •  Jan 25, 2022
JEE
Solution:
Let us first calculate the time taken by Charlie to complete the round trip from A to B and back to A.
Distance between A and B = 5 km
Charlie's speed = 5 km/hr
Time taken to go from A to B = Distance/Speed = 5/5 = 1 hour
Time taken to come back from B to A = Distance/Speed = 5/5 = 1 hour
Total time taken by Charlie to complete the round trip = 1 + 1 = 2 hou
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  • a)
    51
  • b)
    59
  • c)
    57
  • d)
    53
  • e)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Sagar Sharma answered  •  Jun 18, 2024
JEE
Understanding the Problem
The expression "185193 = ?" suggests that we are looking for a value that represents some relationship or calculation involving the number 185193.

Analyzing the Given Options
The options provided are:
- a) 51
- b) 59
- c) 57
- d) 53
- e) None of these

Identifying the Pattern
To determine w
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7.8 + 5.4 x 8.2 = ?
  • a)
    52.08
  • b)
    108.24
  • c)
    48.05
  • d)
    102.05
  • e)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Aarav Sharma answered  •  May 24, 2023
JEE
Multiplying Decimals

To solve this problem, we need to multiply 5.4 and 8.2. Here’s how we’ll do it:

Step 1: Ignore the decimal points and multiply 54 and 82.
54 x 82 = 4428

Step 2: Count the number of decimal places in the numbers we multiplied. There is one decimal place in 5.4 and two decimal places in 8.2, so we’ll add those together to get three decimal p
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Direction: Study the following question carefully and choose the right answer.
If ZOO is coded as 2, TAN is coded as 8, then what is the code for WAR?
  • a)
    3
  • b)
    6
  • c)
    4
  • d)
    7
Correct answer is option 'B'. Can you explain this answer?

Nilesh Joshi answered  •  Apr 07, 2024
JEE

- Explanation:

Explanation of the coding pattern used to decipher the code for "WAR":

- Pattern:
- The code for each letter is determined by its position in the alphabet.
- The position of the letter in the alphabet is multiplied by the number of letters in the word.
- For example, Z (26th letter) is coded as 2 because 26 * 1 = 2. T (20th
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After the division of a number successively by 3, 4 and 7, the remainders obtained are 2, 1 and 4 respectively. What will be the remainder if 84 divides the same number?
  • a)
    80
  • b)
    75
  • c)
    41
  • d)
    53
Correct answer is option 'D'. Can you explain this answer?

Krishna Iyer answered  •  May 09, 2022
JEE
Since after division of a number successively by 3, 4 and 7, the remainders obtained are 2, 1 and 4 respectively, the number is of form ((((4*4)+1)*3)+2)k = 53K.
Let k = 1; the number becomes 53
If it is divided by 84, the remainder is 53.

Hence Option D is correct

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  • a)
    6410
  • b)
    2959
  • c)
    6084
  • d)
    5776
  • e)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Sagar Sharma answered  •  Jul 04, 2019
JEE
Understanding the Equation
We start with the equation:
√7921 × √? = 6942
To simplify this, we can use the property of square roots:
√A × √B = √(A × B)
Therefore, we can rewrite the equation as:
√(7921 × ?) = 6942

Squaring Both Sides
Next, we square both sides to eliminate the square root:
(7921 ×
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The ratio of the income of A and B is 7 : 8, and the ratio of the income of B and C is 8 : 11, If the difference in the income earned by A and C is Rs. 800, then find the sum of income earned by all three of them.
  • a)
    Rs. 5200
  • b)
    Rs. 4800
  • c)
    Rs. 4000
  • d)
    Rs. 3600
Correct answer is option 'A'. Can you explain this answer?

Mainak Majumdar answered  •  Sep 17, 2024
JEE
Given:
Income ratio of A and B = 7 : 8
Income ratio of B and C = 8 : 11
Difference in income between A and C = Rs. 800

To find:
Sum of income earned by all three (A, B, and C)

Approach:
1. Let the income of A, B, and C be 7x, 8x, and 11y respectively.
2. Use the given ratios to form equations and solve them to find the values of x and y.
3.
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  • a)
    510.984
  • b)
    530.56
  • c)
    520.47
  • d)
    520.56
  • e)
    None of these
Correct answer is option 'E'. Can you explain this answer?

Sagar Sharma answered  •  Jul 25, 2024
JEE
Understanding the Equation
To solve the equation \( \frac{4}{439} + ? + 354 = 865 \), we first need to isolate the unknown variable represented by "?".

Step 1: Rearranging the Equation
We can rearrange the equation as follows:
\[
? = 865 - 354 - \frac{4}{439}
\]

Step 2: Calculate the Known Values
Now, let's calculate the valu
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  • a)
    0.668
  • b)
    2.99
  • c)
    0.167
  • d)
    7
  • e)
    none of these
Correct answer is option 'B'. Can you explain this answer?

Prince answered  •  Aug 02, 2024
JEE
Let 4.669 be a and 2.331 be B
then the whole term becomes like
a²-b²/a²+b²-2ab
= (a-b)(a+b) / (a-b)²
= (a+b) / (a-b)
= 4.669 + 2.331 / 4.669 - 2.331
= 7/2.338 = 2.99

Find the highest power of 24 in 150!
  • a)
    46
  • b)
    47
  • c)
    48
  • d)
    49
Correct answer is option 'C'. Can you explain this answer?

Anaya Patel answered  •  Mar 01, 2020
JEE
24 = 8 × 3
Therefore, we need to find the highest power of 8 and 3 in 150!
8 = 23
Highest power of 8 in 150! is:
= [(150 / 2) + (150 / 4) + (150 / 8) + (150 / 16) + (150 / 32) + (150 / 64) +(150 / 128)] / 3
= 48
Highest power of 3 in 150! is:
= [150 / 3] + [150 / 9] + [150 / 27] + [150 / 81]
= 72
As the powers of 8 are less, powers of 24 in 150! = 48

  • a)
    2 - √3
  • b)
    2 + √3
  • c)
    16 - √3
  • d)
    14 - √3
  • e)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Sanjeev Chalapandian answered  •  Aug 09, 2024
JEE
=2+√3/2-√3 +2-√3/2+√3 +√3-1/√3+1
=(2+√3)^2 +(2-√3)^2/2^2-√3^2 +√3-1/√3+1
=8+6/4-3+√3-1/√3+1
=14+(√3-1/√3+1)
=14√3+14+√3-1/√3+1
=15√3+13/√3+1
=(15√3+13)×√3-1/√3^2-1^2
=45 -15√3+13√3-13/3-1
=32-2√3/2
=16-√3
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