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Over the course of a certain month, Olga, a saleswoman, sold 20 cars, and each of her 7 colleagues sold at least 1 car. Did Olga sell as many or more cars than at least 4 of her colleagues?
(1) The average (arithmetic mean) of the number of cars sold by Olga’s 7 colleagues is 12.
(2) The median of the number of cars sold by Olga’s 7 colleagues is 18.
Explanation: Hint: Statement (1): In worst case scenarios, the 7 colleagues sold {21, 21, 21, 18, 1, 1, 1} or {20, 20, 20, 20, 2, 1, 1} cars respectively; still, Olga’s sale exceeds or matches the sale by 4 of her colleagues.
Detailed explanation:The number of cars sold by Olga = 20.
The number of cars sold by each of Olga’s 7 colleagues is at least 1.
We need to find whether the number of cars sold by Olga is greater than at least 4 of her colleagues. Statement (1) The average number of cars sold by Olga’s 7 colleagues is 12, which implies that the
total number of cars sold = 7 x 12 = 84.
Since Olga sold 20 cars,
for at least four of her colleagues to outsell her, each would need to sell a minimum of 21 cars. This would mean that these
four colleagues collectively would have to sell 4 x 21 = 84 cars.
However, this scenario implies that the remaining three colleagues sold zero cars, which
contradicts the given information that each colleague sold at least one car.
Therefore, it is not possible for at least four of her colleagues to sell more cars than she did.
It is possible to determine with certainty that Olga sold as many or more cars than at least 4 of her colleagues.
Hence, Statement (1) is sufficient. Statement (2) Since the
median number of cars sold by Olga's 7 colleagues is 18, it implies that when the number of cars sold by each colleague is arranged in ascending order, the first
four colleagues will each have sold 18 or fewer cars.
It is possible to determine with certainty that Olga sold as many or more cars than at least 4 of her colleagues.
Hence, Statement (2) is sufficient. D is the correct answer choice.