• 7 CATs FREE!
    If you earn 100 Forum Points

    Engage in the Beat The GMAT forums to earn
    100 points for $49 worth of Veritas practice GMATs FREE

    Veritas Prep
    VERITAS PRACTICE GMAT EXAMS
    Earn 10 Points Per Post
    Earn 10 Points Per Thanks
    Earn 10 Points Per Upvote
    REDEEM NOW

An optometrist charges $150 per pair for soft contact lenses

This topic has expert replies
Legendary Member
Posts: 1298
Joined: 29 Oct 2017
Followed by:5 members

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

An optometrist charges $150 per pair for soft contact lenses and $85 per pair for hard contact lenses. Last week she sold 5 more pairs of soft lenses than hard lenses. If her total sales for pairs of contact lenses last week were $1,690, what was the total number of pairs of contact lenses that she sold?

A. 11
B. 13
C. 15
D. 17
E. 19

The OA is B

Source: GMAT Paper Tests

User avatar
GMAT Instructor
Posts: 15495
Joined: 25 May 2010
Location: New York, NY
Thanked: 13060 times
Followed by:1879 members
GMAT Score:790

by GMATGuruNY » Thu Mar 28, 2019 12:42 pm
swerve wrote:An optometrist charges $150 per pair for soft contact lenses and $85 per pair for hard contact lenses. Last week she sold 5 more pairs of soft lenses than hard lenses. If her total sales for pairs of contact lenses last week were $1,690, what was the total number of pairs of contact lenses that she sold?

A. 11
B. 13
C. 15
D. 17
E. 19
Since $150 soft lenses and $85 hard lenses yield $1690 in revenue, we get:
150S + 85H = 1690
30S + 17H = 238

The sum on the left side must yield a units digit of 8.
Since 17*4 = 68, it is likely that H=4:
30S + 17*4 = 338
30S + 68 = 238
30S = 170
S=9

S=9 and H=4 satisfy the condition that the optometrist sells 5 more pairs of soft lenses than hard lenses.
Thus, the total number of pairs = 9+4 = 13.

The correct answer is B.
Mitch Hunt
Private Tutor for the GMAT and GRE
GMATGuruNY@gmail.com

If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon.

Available for tutoring in NYC and long-distance.
For more information, please email me at GMATGuruNY@gmail.com.
Student Review #1
Student Review #2
Student Review #3