Maths Olympiad Prep

Track / Stage 4 / 20 of 340 #280 of 1964

Problem 280

AMC 12 late, AIME early
Combinatorics Difficulty 4.6 Find the answer

191. Three Shepherds. When the Crackhams approached a large city, they had to stop because a flock of sheep was moving along the road, followed by a herd of bulls, and then the shepherds were driving a herd of horses. The Crackhams realized that it was market day in the city today. George, taking advantage of the opportunity, came up with the following puzzle.

Three shepherds driving their herds met on a highway. Jack said to Jim:

- If I give you 6 pigs for one horse, then your herd will have twice as many heads as mine.

And Dan remarked to Jack:

- If I give you 14 sheep for one horse, then your herd will have three times as many heads as mine.

Jim, in turn, said to Dan:

- And if I give you 4 cows for one horse, then your herd will be six times larger than mine.

The deals did not go through, but could you still tell how many heads of livestock there were in the three herds.

A number or a short expression. Spacing, $ signs and \frac vs / are all fine.

Official solution

191. Jack had 11 heads of cattle, Jim had 7, and Dan had 21, which is a total of 39 heads of cattle.

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