Three numbers are in the ratio 1/4, 5/9, 7/12. The…

Comprehension:
In the following passage, some words have been deleted. Select the most appropriate option
to fill in each blank.
In the 19th century, there was an industrial revolution in Europe. As a result, millions of people
left the (1) ______ and went to work in big factories in cities. Today, it is the reverse. In several
major cities, people have started moving out. Why? They want a cleaner, (2) ______
environment. There are fewer jobs in ‘heavy’ industries like steel and power generation. (3)
______, there are more jobs in service industries like banking, tourism and food delivery.
Besides, modern transport and communications have made it easier for people to (4) ______
to work or even work from home. The result of this revolution in the 21st century will be
‘spread cities’ – cities are growing fast, but (5) ______, away from city centres and people are
choosing to live 40, 50 or 60 kilometres away.

Three numbers are in the ratio 1/4, 5/9, 7/12. The difference between the greatest and the smallest number is 180. Find the sum of all the three numbers.

Show answer & explanation

Correct answer: C

Explanation

The correct answer is option 3 i.e. 750.

The ratio of three numbers = 1/4 : 5/9 : 7/12

Let the numbers be = x,y,z

Taking the LCM of the denominators,

LCM (4, 9, 12) = 36

⇒ 1/4 × 36 , 5/9 × 36 , 7/12 × 36

⇒ x : y : z = 9 : 20 : 21

∵ z - x = (21x - 9x) = 12x = 180

⇒ x = 15

x = (9 × 15) , y = (20 × 15) , z = (21 × 15)

x = 135 , y = 300 , z = 315

sum of x,y,z = (135 + 300 + 315) = 750

SSC CHSL 2021 PYQ — Question 71