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All questions of Unitary Method for Grade 7 Exam

If 2, 3, 28 and x are in proportion then find the value of x.
  • a)
    42
  • b)
    28
  • c)
    56
  • d)
    14
Correct answer is option 'A'. Can you explain this answer?

Let present age of father be 7x and that of son is 2x
after 10 years, their ages will be 7x+10 and 2x+10 respectively
so ratio will be
(7x+10)/(2x+10) = 9/4
28x+40 = 18x+90
10x = 50
x = 5
so present age of father is 7x =
35 years
 

If 3, 8 and15 ,x are in proportion then find the value of x.
  • a)
    15
  • b)
    20
  • c)
    40
  • d)
    30
Correct answer is option 'C'. Can you explain this answer?

Harshad Goyal answered
Given, 3:8::15:x

To find the value of x, we can use the property of proportionality which states that the product of the means is equal to the product of the extremes.

In other words, 3 * x = 8 * 15

Simplifying further, we get:

3x = 120

x = 40

Therefore, the value of x is 40, which corresponds to option C.

If x, 30,24 and 16 are in proportion then find the value of x.
  • a)
    45
  • b)
    60
  • c)
    15
  • d)
    80
Correct answer is option 'A'. Can you explain this answer?

Mahesh Chavan answered
Given: x, 30, 24, 16 are in proportion.

To find: The value of x.

Solution:

The given numbers are in proportion. This means that the ratio of any two consecutive numbers is equal to the ratio of the other two consecutive numbers.

Therefore, we can write:

x/30 = 24/16

Cross-multiplying, we get:

16x = 30 × 24

Simplifying, we get:

16x = 720

Dividing both sides by 16, we get:

x = 45

Therefore, the value of x is 45.

Hence, option A is the correct answer.

If 5, 30, 3 and x are in proportion then find the value of x.
  • a)
    24
  • b)
    6
  • c)
    18
  • d)
    15
Correct answer is option 'C'. Can you explain this answer?

Manasa Saha answered
Finding the value of x in proportion

Given: 5, 30, 3, and x are in proportion.

To solve for x, we need to set up a proportion. In a proportion, the product of the means is equal to the product of the extremes. Therefore, we can write:

5/30 = 3/x

To solve for x, we can cross-multiply:

5x = 90

x = 18

Therefore, the value of x is 18.

Answer: Option C (18)

What is the new ratio obtained by adding 4 to the antecedent and 2 to the consequent of the ratio 3:8?
  • a)
    5:12 
  • b)
    10:7
  • c)
    12:5
  • d)
    7:10              
Correct answer is option 'D'. Can you explain this answer?

Given ratio is 3:8.

To obtain the new ratio, we need to add 4 to the antecedent and 2 to the consequent.

Adding 4 to the antecedent of 3, we get 7.
Adding 2 to the consequent of 8, we get 10.

Therefore, the new ratio is 7:10.

Hence, the correct answer is option D.

If 9, 18, x and 8 are in proportion then find the value of x.
  • a)
    2
  • b)
    4
  • c)
    3
  • d)
    None of these
Correct answer is option 'B'. Can you explain this answer?

Neha Mehta answered
Given: 9, 18, x, 8 are in proportion

To find: value of x

Solution:

We know that when four numbers are in proportion, the product of the extremes is equal to the product of the means.

So, we can write:

9 × 8 = 18 × x

72 = 18x

4 = x

Therefore, the value of x is 4.

Hence, option B is the correct answer.

In a school, there were 73 holidays in one year. What is the ratio of the number of holidays to the number of days in one year?
  • a)
    it is 5:1
  • b)
    it is 1:5
  • c)
    it is 1:4
  • d)
    None of these
Correct answer is option 'B'. Can you explain this answer?

Gayatri Chavan answered
Given:
Number of holidays in a year = 73.
To do:
We have to find the ratio of the number of holidays to the number of days in one year.
Solution:
Number of days in a year = 365.
Therefore,
The ratio of the number of holidays to the number of days in one year = 73:365 = 1:5.

The ratio of number of boys to number of girls in a tutorial is 2:3. If there are 180 girls, what is the number of boys?
  • a)
    36  
  • b)
    60
  • c)
    120
  • d)
    100
Correct answer is option 'C'. Can you explain this answer?

Uday Gupta answered
Ratio of number of boys to number of girls = 2:3
Number of girls = 180
Let the number of boys be x.
⇒ 2/3 = x/180 [∵ they are equivalent ratios]
⇒ 3x = 2×180
⇒ x = 360/3
⇒ x = 120
∴ Number of boys are 120.

What are the extremes of the proportion 9:3::36:12?
  • a)
    9, 3    
  • b)
    36, 12
  • c)
    3, 36
  • d)
    9, 12
Correct answer is option 'D'. Can you explain this answer?

Manasa Saha answered
To solve this proportion, we need to determine the relationship between the first pair of numbers and apply the same relationship to the second pair of numbers.

In the given proportion, 9:3 and 36:12, we can see that both pairs have a ratio of 3:1. This means that for every 3 in the first pair, there is 1 in the second pair.

To find the extremes of the proportion, we need to identify the first and last numbers in each pair. In the first pair, the first number is 9 and the last number is 3. In the second pair, the first number is 36 and the last number is 12.

Therefore, the extremes of the proportion are 9 and 12.

Hence, the correct answer is option D) 9, 12.

The ratios 6:3 and 5 :15 are given. Which of the following is true about them?
  • a)
    The given ratios are not in proportion
  • b)
    The given ratios are equal
  • c)
    The given ratios are equivalent
  • d)
    The given ratios are in proportion
Correct answer is option 'A'. Can you explain this answer?

Sanky Bhim answered
-when two ratios are same they are said to be in proportion.
- suppose we write the two ratios like this ---> 6:3::5:15 ( :: means same as )
- but 6:3 is not same as 5:15 
- to check it we know product of extremes = product of means 
- 6 * 15 = 90
-3* 5 = 15
- 90 is not equal to 15 hence the given ratios are not in proportion .

If 14, 16, x and 24 are in proportion then find the value of x.
  • a)
    10.5
  • b)
    21
  • c)
    5
  • d)
    None of these
Correct answer is option 'B'. Can you explain this answer?

Dishani Pillai answered
Given: 14, 16, x and 24 are in proportion.

To find: Value of x.

Solution:

When four numbers are in proportion, it means that the product of the first and fourth numbers is equal to the product of the second and third numbers.

Therefore, we can write:

14 × 24 = 16 × x

336 = 16x

x = 336/16

x = 21

Hence, the value of x is 21.

Therefore, option (B) is the correct answer.

Find the ratio of 30 minutes to 1.5 hours.
  • a)
    it is 1:3
  • b)
    it is 3:1
  • c)
    it is 1:2
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Pallavi Roy answered
To find the ratio of 30 minutes to 1.5 hours, we need to convert both quantities to the same unit of time. Since both minutes and hours are units of time, we can convert minutes to hours or hours to minutes. In this case, it would be easier to convert minutes to hours.

Converting 30 minutes to hours:
1 hour = 60 minutes
So, 30 minutes = 30/60 = 0.5 hours

Now we can compare the two quantities in terms of hours:

30 minutes : 1.5 hours
0.5 hours : 1.5 hours

Simplifying the ratio:
Divide both quantities by the same number to simplify the ratio. In this case, we can divide both quantities by 0.5.

0.5 hours / 0.5 hours : 1.5 hours / 0.5 hours
1 : 3

Therefore, the ratio of 30 minutes to 1.5 hours is 1:3.

Explanation:
- Convert 30 minutes to hours by dividing it by 60.
- Compare the two quantities in terms of hours.
- Simplify the ratio by dividing both quantities by the same number.
- The simplified ratio is 1:3.

The ratio of 90 cm to 1.5 m is ______.
  • a)
    it is 3:5
  • b)
    it is 1:5
  • c)
    it is 5:3
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Saikat Pillai answered
Understanding the Ratio
To find the ratio of 90 cm to 1.5 m, we first need to convert both measurements to the same unit. Here, we will convert 1.5 m to centimeters.
Step 1: Convert Meters to Centimeters
- 1 meter = 100 centimeters
- Therefore, 1.5 meters = 1.5 × 100 = 150 centimeters
Step 2: Set Up the Ratio
Now that we have both measurements in centimeters, we can set up the ratio:
- The ratio of 90 cm to 150 cm can be written as 90:150.
Step 3: Simplify the Ratio
To simplify the ratio, we divide both sides by their greatest common divisor (GCD).
- The GCD of 90 and 150 is 30.
Now, divide both numbers by 30:
- 90 ÷ 30 = 3
- 150 ÷ 30 = 5
So, the simplified ratio is:
- 3:5
Conclusion
The ratio of 90 cm to 1.5 m is indeed 3:5. Therefore, the correct answer is option 'A'.

Length of a room is 30 m and its breadth is 20 m. Find the ratio of length of the room to the breadth of the room.
  • a)
    it is 2:3
  • b)
    it is 3:2
  • c)
    it is 1:3
  • d)
    it is 1:2
Correct answer is option 'B'. Can you explain this answer?

Jay Goyal answered
To find the ratio of length to breadth, we need to divide the length of the room by the breadth of the room.

Given:
Length of the room = 30 m
Breadth of the room = 20 m

To find the ratio of length to breadth, we divide the length by the breadth:

Ratio = Length / Breadth

Let's calculate:

Ratio = 30 m / 20 m

Simplifying the division, we get:

Ratio = 3/2

Thus, the ratio of length to breadth is 3:2, which corresponds to option B.

Explanation:
The ratio of length to breadth represents the relationship between the length and breadth of the room. In this case, the length is 30 m and the breadth is 20 m. When we divide the length by the breadth, we get a ratio of 3/2. This means that for every 3 units of length, there are 2 units of breadth. So, the ratio of length to breadth is 3:2.

6 : 4 is equivalent ratio of ______.
  • a)
    it is 3:2
  • b)
    it is 2:3
  • c)
    it is 1:2
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

To determine the equivalent ratio of 6:4, we need to find a ratio that is proportional to 6:4. In other words, we need to find a ratio that can be obtained by multiplying both the numerator and denominator of 6:4 by the same number.

Let's try multiplying 6 and 4 by 1/2:

(6 * 1/2) : (4 * 1/2)
= 3 : 2

So, the equivalent ratio of 6:4 is 3:2. This means that for every 6 units in the first quantity, there are 4 units in the second quantity, and this is the same as saying that for every 3 units in the first quantity, there are 2 units in the second quantity.

Hence, the correct answer is option A: it is 3:2.

Find the ratio of 81 to 108.
  • a)
    it is 1:4
  • b)
    it is 4:3
  • c)
    it is 3:4
  • d)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Saikat Rane answered
Ratio refers to the quantitative relationship between two amounts or values. It is expressed in the form of a:b, where a and b are the two values being compared.

To find the ratio of 81 to 108, we need to divide both numbers by their greatest common factor, which is 27.

81 ÷ 27 = 3
108 ÷ 27 = 4

Therefore, the ratio of 81 to 108 is 3:4.

Option C, "it is 3:4", is the correct answer.

What is the condition for two ratios to be equal?
  • a)
    Product of means is equal to antecedents
  • b)
    Product of extremes is equal to consequents
  • c)
    Antecedents   are   equal   to consequents
  • d)
    Product of means is equal to product of extremes
Correct answer is option 'D'. Can you explain this answer?

Maya Deshpande answered
Ratios:
A ratio is a comparison of two quantities. It is expressed in the form of a fraction or using a colon (:). For example, if we have two quantities A and B, the ratio of A to B can be written as A/B or A:B.

Equality of Ratios:
Two ratios are said to be equal if they represent the same comparison between quantities. In other words, the two ratios have the same value.

Conditions for Ratios to be Equal:
To determine if two ratios are equal, we can use different methods. However, the most common condition for two ratios to be equal is when the product of the means is equal to the product of the extremes.

Explanation:
Let's consider two ratios, A/B and C/D. According to the condition for equality of ratios, we have the following equation:

(A/B) = (C/D)

To check if the condition holds true, we can cross multiply the terms:

A * D = B * C

If the product of the means (B * C) is equal to the product of the extremes (A * D), then the two ratios are equal.

Example:
Let's take an example to understand this concept better. Consider the ratios 2/3 and 4/6. We can check if they are equal using the condition mentioned above:

Product of means = (3 * 4) = 12
Product of extremes = (2 * 6) = 12

Since the product of the means is equal to the product of the extremes (12 = 12), the two ratios are equal.

Conclusion:
In summary, two ratios are equal if the product of the means is equal to the product of the extremes. This condition allows us to determine if two ratios represent the same comparison between quantities.

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