BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Set Algebra

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 21
Joined: Thu Oct 01, 2020 4:48 am
Followed by:1 members

Set Algebra

by alishagmat » Fri Oct 02, 2020 4:14 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

In a shop, 40% socks are white and rest are black. 60% socks are made of cotton and rest are made of wool. 25% white socks are made of cotton and 20 of the black socks are made of wool. How many black socks are made of cotton?

(A) 100
(B) 80
(C) 60
(D) 50
(E) 25
Top
Source: — Data Sufficiency |
Legendary Member
Posts: 2214
Joined: Fri Mar 02, 2018 2:22 pm
Followed by:5 members

Re: Set Algebra

by deloitte247 » Thu Oct 08, 2020 9:14 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Given that white socks = 40%
Cotton socks = 60%
White socks with cotton = 25% of white socks
Black socks with wool =20
Let total no. of socks = x
White socks = 0.4x
Black socks = x - 0.4x = 0.6x
Cotton socks = 0.6x wool socks = x - 0.6x = 0.4x
White socks with cotton = 25% of white socks = 25% of 0.4x = 0.1x
White socks with wool = total white socks - white socks with cotton
= 0.4x - 0.1x = 0.3x
Black socks with wool = 20
Total socks with wool = white socks with wool + black socks with wool
0.4x = 0.3x + 20
0.4x - 0.3x = 20
0.1x = 20
x = 20/0.1 = 200
Total black socks = black socks with cotten + black socks with wool
Black socks with cotten = total black socks - black socks with wool
= 0.6x - 20 where x = 200
= 0.6(200) - 20
= 120 - 20
= 100
Answer = option A
Top
Post new topic Post Reply
• Page 1 of 1