A bakery sold an average(arithmetic mean) of \(820\) cookies per day in an operating period. On "good" days, the bakery

[Gmat_mission]

A bakery sold an average(arithmetic mean) of \(820\) cookies per day in an operating period. On "good" days, the bakery sold an average of \(980\) cookies per day, and on "fair" days, the bakery sold an average of \(640\) cookies per day. If every day in the operating period was either "good" or "fair", what was the ratio of the number of "good" days to the number of "fair" days for the bakery's operating period?

a) \(2:1\)
b) \(3:2\)
c) \(5:4\)
d) \(7:6\)
e) \(9:8\)

Answer: E

Source: Veritas Prep

[Scott@TargetTestPrep]

A bakery sold an average(arithmetic mean) of \(820\) cookies per day in an operating period. On "good" days, the bakery sold an average of \(980\) cookies per day, and on "fair" days, the bakery sold an average of \(640\) cookies per day. If every day in the operating period was either "good" or "fair", what was the ratio of the number of "good" days to the number of "fair" days for the bakery's operating period?

a) \(2:1\)
b) \(3:2\)
c) \(5:4\)
d) \(7:6\)
e) \(9:8\)

Answer: E

Solution:

We are given that a bakery sold an average (arithmetic mean) of 820 cookies per day in an operating period, and that on good days the bakery sold an average of 980 cookies per day, and on fair days the bakery sold an average of 640 cookies per day.

If we let G = the number of good days and F = the number of fair days, we can create the following equation:

820 = (980G + 640F)/(G + F)

820G + 820F = 980G + 640F

180F = 160G

9F = 8G

G/F = 9/8

Answer: E