Question

(b) What is 50% of a number whose 200% is 20 ?
1)15
2)5
3)20
4)10​

Answer 1

Let the number X

Given that 200% of X=20

$⇒ \frac{100}{20} \times \: X = 20$

$⇒X = 10$

$Now \: 50 \: percent \: of \: X = \frac{50}{100} \times 10$

$⇒50 \: percent \: of \: X \: = \frac{1}{2} \times 10 \: = 5$

therefore option (2) 5 is the answer.

Answer 2

Answer :-

• Option 2) is correct.

• 5 is 50% of the number whose 200% is 20.

Step-by-step explanation :-

• To find the answer, we first have to find out the number who's 200% is 20.

• Let the number be x.

• Given, 200% of x is 20.

• We will use this information to find out the number.

Let's proceed!

$\sf200\% \: of \: x = 20$

Converting 200% into fraction,

$\sf\dfrac{2\!\!\!\not0 \!\!\!\not0}{1\!\!\! \not0 \!\!\!\not0} \times x = 20$

Reducing the numbers,

$\sf\dfrac{2}{1} \times x = 20$

Multiplying $\sf \dfrac{2}{1}$ by x,

$\sf \dfrac{2x}{1} = 20$

Transposing 1 from LHS to RHS, changing it's sign,

$\sf2x = 20 \times 1$

Multiplying the numbers,

$\sf2x = 20$

Transposing 2 from LHS to RHS, changing it's sign,

$\sf x = \dfrac{20}{2}$

Dividing 20 by 2,

$\sf x = 10$

Therefore, 200% of 10 is 20.

• Now, in the question, we are asked to find 50% of the number who's 200% is 20.

• We already found out the required number.

• So, now that means we have to find 50% of 10.

Let's start!

$\sf50\% \: of \: 10$

Converting 50% into fraction,

$\sf \dfrac{5 \!\!\!\not0}{1 \!\!\!\not0 \!\!\!\not0} \times 1 \! \! \!\not0$

$\sf\dfrac{5}{1} \times 1$

$\sf\dfrac{5}{1}$ can also be written as 5.

$\sf5 \times 1$

$\sf\Rightarrow5.$

50% of 10 = 5.

So, that means, 50% of the number whose 200% is 20 = 5.

Therefore, option 2) is correct.