Two Friends, Whom We Will Call Arthur and Robert, Were

16. Two Friends, Whom We Will Call Arthur and Robert, Were

Two friends, whom we will call Arthur and Robert, were curators at the Museum of American History. Both were born in the month of May, one in 1932 and the other a year later.

Each was in charge of a beautiful antique clock. Both of the clocks worked pretty well, considering their ages, but one of them lost ten seconds an hour and the other gained ten seconds an hour.

On one bright day in January, the two friends set both clocks right at exactly 12 noon.

``You realize,'' said Arthur, ``that the clocks will start drifting apart, and they won't be together again until---let's see---why, on the very day you will be 47 years old. Am I right?''

Robert then made a short calculation. ``That's right!'' he said.

Who is older, Arthur or Robert?

Submitted by tartle · Added 11 April 2010

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Solution:

Arthur is actually the younger friend, born in May 1933, while Robert was born in May 1932. The clocks will drift apart due to one gaining and the other losing time, and they will align again when Robert turns 47 on May 1, 1979, which means the clocks were set right on January 31, 1979, in a non-leap year.

Comments (1)

ChibiHoshi ★ Solved 18 March 2011

The clock would have been set in either 1979 or 1980 for one of them to turn 47. (1932 or 1933 birth year)

The clocks will resync in 90 days. (Simple conversion calculation of 10s/hr would take 90 days to lose/gain 6 hours which is when both would resync)

The Jan-May gap could only work if it was set 31st January and a non-leap year (1980 was a leap year and therefore the clock would have synced on April 30th)

So Robert, the one reaching 47 on May 1st of 1979 was the one born in 1932 and older

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