Name: Multiplication of Three-digit Numbers
Uploaded: 2019-07-19
Duration: 6 min 16 s
Description: This video will teach you how to do long multiplication. Knowing how to do long multiplication is an important skill, and we can learn it easily.

Question

A boy has as many sisters as brothers, and his sisters have half as many sisters as brother. how many boys and girls are there in the family?

Accepted Answer

Let the number of sisters $= x$ and brothers $= y$ .
“A boy has as many sisters as brothers” means $y = x$ .
According to the problem statement, we have to increase the number of boys by $1$ to account for the boy himself.
So, total number of boys $\Rightarrow y = x + 1 \dots (i)$
“His sisters have half as many sisters as brothers” means $x = \frac{y}{2}$ .
Now, according to the line, we have to increase the number of girls by $1$ to account for one sister herself.
So, total number of girls $\Rightarrow x = \frac{y}{2} + 1 . . . . (i i)$

Put the value of $x$ from equation $(i i)$ in equation $(i)$ , we get,
$y = \frac{y}{2} + 1 + 1$
$\Rightarrow y = \frac{y}{2} + 2$
$\Rightarrow y - \frac{y}{2} = 2$
$\Rightarrow \frac{y}{1} - \frac{y}{2} = 2$
Take LCM of $1 a n d 2$ , i.e., $2$
$\frac{2 y - y}{2} = 2$
$\Rightarrow \frac{y}{2} = 2$
$\Rightarrow y = 2 \times 2 = 4 .$
Put the value of $y$ in equation $(i i)$
$x = \frac{4}{2} + 1$
$\Rightarrow x = 2 + 1 = 3 .$
Hence, total number of boys in the family $= 4$ .
And, total number of girls in the family $= 3$ .

Jharne De and Ranjana Kumar Solutions for Chapter: Playing with Numbers, Exercise 2: Exercise

Jharne De Mathematics Solutions for Exercise - Jharne De and Ranjana Kumar Solutions for Chapter: Playing with Numbers, Exercise 2: Exercise

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