Dividing Mixed numbers

Question

A machine can make a box in 3 17/20 seconds. Estimate the number of boxes it can make in 33 1/2 seconds.

Answer 1

Since we are estimating and not computing, I would convert each mixed number to a decimal.

 

17/20 = 8.5/10 or about 85%

1/2 = 5/10 or about 50%

 

So we now have 33.5 divided by the time per box or 3.85 equals what.

 

33/3 is 10 but that will not work because we still have the .5 and .85 to think about. So an estimate will be around 8.5 to 9.

 

Using a calculator to compute we see that 33.5 / 3.85 is 8.7 so either answer should be acceptable.

 

Ted Breslin, M.Ed.