Bunuel wrote:

Joan walks 4 feet per second, which is half as fast as Al walks. If Bob is twice as fast as Al then how far will Bob walk in a minute?

A. 960 feet

B. 480 feet

C. 240 feet

D. 60 feet

E. 16 feet

When there is just one conversion, here, from seconds to minutes, I find it faster to convert before calculating.

Joan is half as fast as Al => Al is twice as fast as Joan, and Bob is twice as fast as Al.

Start with Joan, convert her rate, multiply by 2, then multiply by 2 again.

Joan = \(\frac{4 ft}{1 sec}\) x \(\frac{60}{60}\) = \(\frac{240 ft}{60 secs}\) = \(\frac{240 ft}{1 min}\), times 2 =>

Al = \(\frac{480 ft}{1 min}\), times 2 =>

Bob = \(\frac{960 ft}{1 min}\) Answer A.

_________________

In the depths of winter, I finally learned

that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"