Happy new year! Today’s SAT question of the day is a math question about stamps and envelopes.  How many more years before no one will know what those are??  Anyhow, the question is as follows:

A machine can insert letters in envelopes at the rate of 120 per minute. Another machine can stamp the envelopes at the rate of 3 per second. How many such stamping machines are needed to keep up with 18 inserting machines of this kind?

They’ve kindly underlined the first thing that we need to look at: we have a units mismatch.  One machine is in envelopes per minute, but the other is in envelopes per second. Continue reading →