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Last Updated on May 5, 2023
GMAT OFFICIAL GUIDE PS
Solution:
The bakery began the day with 40 dozen rolls. Half of the rolls were sold by noon, so we know by noon we had 40 x ½ = 20 dozen rolls sold. It follows that there were 20 dozen rolls remaining between noon and closing time.
We are next given that 80% of the remaining rolls were sold between noon and closing time. Since 80% were sold, 20% were left. This means:
rolls left when the bakery closed = 0.2 x 20 = 4 dozen rolls
Answer: D
