Question

1. In a population of 900, the number of married
couples is as much as the number of singles.
There are 100 twins of which 50 twins are
singles. The population has 400 females in
all. What is the number of married persons ?
(A) 325
(B) 600
(C) 250
(D) 300​

Answer 1

We have

Total population = 900

and No. of singles = No. of married couples

Let No. of singles = x

Then No. of Married persons = 2x

Now, the total population is given by

No. of singles + No. of married persons = 900

⇒ x + 2x = 900

⇒ 3x = 900

⇒ x = 300

Since the No. of Single persons = 300

∴ No. of Married Couples = 2x = 2× 300 = 600

Hence, Option (b) is correct.

Answer 2

Answer:

The correct answer is option (B) 600.

The number of married persons is 600.

Given:

Total persons, n = 900

Number of married couples = Number of singles

Number of twins = 100

Number of twins who are single = 50

Number of females = 400

Find:

The number of married persons.

Solution:

Let P be a person who belongs to the given population. Now, P is either married or single.

Total persons, n = 900

Married persons + Singles = 900           --------------------- (i)

Given that,

Number of married couples = Number of singles

But Number of married couples = Number of married persons/2

∴ Number of singles = Number of married persons/2

Let the number of married persons be p.

Number of singles = p/2

From (i), we have

p + p/2 = 900

(2p + p)/2 = 900

3p/2 = 900

3p = 900×2

3p = 1800

p = 1800/3

p = 600

Hence, the number of married persons, p = 600.

So, option (B) is the correct answer.

#SPJ2