GMAT Practice Question: Last year, sales at Company X were 10 % greater in February than in January, 15%...
Question
Last year, sales at Company X were 10 % greater in February than in January, 15% less in March than in February, 20% greater in April than in March, 10% less in May than in April, and 5 % greater in June than in May. In which month were sales closest to the sales in January?
- February
- March
- April
- May
- June
Topics: percentages, word problems, relative changes, revenue/cost, translations, approximations
Solution
Step 1
We define variables for the sales in each month using clear names to avoid ambiguity.
Jan = sales in January Feb = sales in February Mar = sales in March Apr = sales in April May = sales in May Jun = sales in June
Step 2
We translate "sales at Company X were 10% greater in February than in January" into a multiplication factor.
Feb = 1.10 Jan
Step 3
We translate "15% less in March than in February" into a multiplication factor.
Mar = 0.85 Feb
Step 4
We translate "20% greater in April than in March" into a multiplication factor.
Apr = 1.20 Mar
Step 5
We translate "10% less in May than in April" into a multiplication factor.
May = 0.90 Apr
Step 6
We translate "5% greater in June than in May" into a multiplication factor.
Jun = 1.05 May
Step 7
We express each month's sales as a multiple of January sales by chaining the factors and apply rounding for simplicity.
Feb = 1.10 Jan Mar = 0.85 (1.10 Jan) = 0.935 Jan Apr = 1.20 (0.935 Jan) = 1.122 Jan 1.12 Jan May = 0.90 (1.122 Jan) = 1.0098 Jan 1.01 Jan Jun = 1.05 (1.0098 Jan) = 1.06029 Jan 1.06 Jan
Step 8
We calculate the absolute deviation of each month's factor from 1 (January) to find which is smallest.
|1.10 - 1.00| = 0.10 |0.935 - 1.00| = 0.065 |1.122 - 1.00| = 0.122 |1.01 - 1.00| = 0.01 |1.06 - 1.00| = 0.06
Step 9
We see that May's deviation (0.01) is the smallest, so May's sales are closest to January's.
May is closest because 0.01 is the smallest deviation.
Answer
May, because the sales in May (1.01) have the smallest deviation (0.01) from January sales.
