GMAT Practice Question: Beth has a collection of 8 boxes of clothing for a charity, and the average (arithmetic mean)...
Question
Beth has a collection of 8 boxes of clothing for a charity, and the average (arithmetic mean) number of pieces of clothing per box is c. If she replaces a box in the collection that contains 12 pieces of clothing with a box that contains 22 pieces of clothing, what is the average number of pieces of clothing per box for the new collection, in terms of c ?
- c-\frac{5}{4}
- c+\frac{5}{4}
- 8-\frac{10}{\mathrm{c}}
- 8+\frac{10}{\mathrm{c}}
- 8 c-10
Topics: mean, word problems, translations
Solution
Step 1
We start by defining a variable for the total number of pieces of clothing across all 8 boxes and translate the given average.
T = 8c
Step 2
We compute the new total after removing the 12-piece box and adding the 22-piece box.
T_{\text{new}} = T - 12 + 22
Step 3
We find the new average by dividing the updated total by 8 and then simplify the fraction.
\frac{T_{\text{new}}}{8} = \frac{8c + 10}{8} = c + \frac{10}{8} = c + \frac{\cancel{2}\times5}{\cancel{2}\times4} = c + \frac{5}{4}
Answer
B
