Proportional Reasoning 1 Class 8 Very Short Question Answer

Proportional Reasoning 1 Class 8 Very Short Question Answer

Proportional Reasoning 1 Class 8 Very Short Question Answer

Question 1.

If 3 : 5 :: x: 20, find the value of x.

Solution:

5 × x = 3 × 20

So, x = [latex]\frac{3 \times 20}{5}[/latex] = 12

Question 2.

If y : 45 = 24 : 60, find the value of y.

Solution:

y × 60 = 45 × 24.

So, y = [latex]\frac{45 \times 24}{60}=\frac{3 \times 24}{4}[/latex] = 3 × 6 = 18

Question 3.

An office opens at 9 a.m. and closes at 5.30 p.m. with a lunch break of 30 minutes. What is the ratio of lunch break to the total period in the office?

Solution:

Total period of office

= 5:30 pm - 9 : 00 a.m.

= 17 : 30 - 9 : 00

= 8:30 hours = 8[latex]\frac{1}{2}[/latex] hours = [latex]\frac{17}{2}[/latex] hours

Lunch break = [latex]\frac{1}{2}[/latex] hour

So, required ratio = [latex]\frac{1}{2}[/latex] : [latex]\frac{17}{2}[/latex] = 1 : 17

Question 4.

The shadow of a 3 m long stick is 4 m long. At the same time of the day, if the shadow of a flagstaff is 24 m long, how tall is the flagstaff?

Solution:

Let the the flagstaff be x m tall.

So, 3 : 4 : : x : 24

or 4 × x = 3 × 24.

That is, x = [latex]\frac{3 \times 24}{4}[/latex] = 18 m.

Question 5.

A 3 metre long metal pipe was found to weigh 7.6 kg. What would be the weight of the same type of 7.8 m long metal pipe?

Solution:

Let the weight of such a pipe be x kg.

So, 3 : 7.6 : : 7.8 : x

or 3 × x = 7.6 × 7.8

or x = [latex]\frac{7.6 \times 7.8}{3}[/latex] = 7.6 × 2.6

= 19.76 kg.