Percentage, Ex- 9B

Question

Can anyone please solve these questions?

Answer 1

13. (A) \(18\frac 34\)%

A complete day i.e 24 hours is 100% .

24 hours = 24 × 60 mins = 1440 mins

4 hours, 30 mins = 270 mins

1440 mins = 100% of the day

270 mins = \( \frac {270 \times 100}{1440}\)

= 18.75% or \(18\frac 34\)%

16. (c) 120

Let the number = Z

∴ Z - (\(27\frac {1}2\) ÷ of z) = 87

⇒ Z - (Z × \(\frac{55}2\) × \(\frac 1{100}\)) = 87

⇒ Z - (Z × \(\frac {11}{2}\) × \(\frac 1{20}\)) = 87

⇒ Z - (\(\frac {11Z}{40}\)) = 87

⇒ \(\frac {29Z}{40}\) = 87

⇒ Z = 87 × \(\frac {40}{29}\)

⇒ Z = 120

17. (c) 0.25%

Given number is 0.05

⇒ \(\frac {0.05}{20} \times 100 = 0.25\%\)

18. (d) 300%

Percentage = {(\(\frac13\) × 1206) × (\(\frac 1{134}\)) × 100}%

= {402 × \(\frac 1{134}\) × 100} %

= {3 × 100} %

= 300%

19. (a) x

x% of y = \(\frac x{100}\) × y

Let this be equal to y% of k,

⇒ \(\frac y{100} \times k = \frac {xy}{100}\)

∴ k = x

x% of y is y% of x.

Answer 2

13. The correct option is (a) \(18 \frac{3}{4}\) %

A complete day i.e 24 hours is 100 %.

24 hours = 24 × 60 mins = 1440 mins

4 hours, 30 mins = 270 mins

1440 mins = 100% of the day

270 mins = ?

= \(\frac{270 \times 100}{1440}\)

= 18.75%

4 hours and 30 minutes is 18.75% of a day.

16. The correct option is (c) 120.

Let the number = x 

∴ x - (\(27\frac{1}{2}\) ÷ of x) = 87

⇒ x - (x × 55/2 × 1/100) = 87  

⇒ x - (x × 11/2 × 1/20) = 87  

⇒ x - (11x/40) = 87 

⇒ 29x/40 = 87  

⇒ 29x/40 = 87  

⇒ x = 87 × 40/29  

⇒ x = 120

18. The correct option is (d) 300%

One-third of 1206 = 1/3 x 1206 = 402

Let x% of 134 be 402

\(\frac{x}{100} \times 134 = 402\)

\(x = \frac{100 \times 402}{134} = 300\)

So, 300% of 134 is 402.

19. The correct option is (a) x.

Let x% of y = y% of z.

x/100 × y = y/100 × z

z = x

Therefore,

x% of y = y% of x.