All but 4 of the counselors at a certain summer camp have a sailing certification, first aid certification, or both. If twice as many of the counselors have neither certification as having both certifications, 7 of the counselors have a sailing certification, and there are a total of 22 counselors on staff, then how many of the counselors have a first aid certification?
A) 7
B) 9
C) 11
D) 13
E) 15
Answer: D
Source: Economist
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
All but 4 of the counselors at a certain summer camp have a sailing certification, first aid certification, or both. If
This topic has expert replies
GMAT/MBA Expert
-
Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7242
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
Solution:Vincen wrote: ↑Sun Feb 14, 2021 12:05 pmAll but 4 of the counselors at a certain summer camp have a sailing certification, first aid certification, or both. If twice as many of the counselors have neither certification as having both certifications, 7 of the counselors have a sailing certification, and there are a total of 22 counselors on staff, then how many of the counselors have a first aid certification?
A) 7
B) 9
C) 11
D) 13
E) 15
Answer: D
We can use the formula:
Total = Sailing + First Aid - Both + Neither
We are given that Total = 22, Sailing = 7 and Neither = 4. Since we are also given that Neither is twice Both, then Both = 2. Therefore, we have:
22 = 7 + First Aid - 2 + 4
22 = 9 + First Aid
13 = First Aid
Answer: D
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
