SAT Question of the Day July 18th 2013

In a certain lawn-mower factory, 0.06 percent of all mowers produced are defective. On the average, there will be 3 defective mowers out of how many produced?

A.     500

B.     1800

C.     5000

D.     18000

E.     50000

We have a percentage problem on our hands.

We recall that 1% means 1 out of a hundred. If we had 0.1% – that implies that 0.1% is 0.1 out of a 100 and if we have 0.01% that means 0.01% is 0.01 out of a 100. How many times does 0.01 fit in 100? 100/0.01=10,000.

Now we have 0.06% or six times that number. This in-turn tells us we can expect to see 6 defective lawn mowers out of every 10,000. We observed only 3 such defective lawn mowers so we probably checked only half of 10,000 or 5,000 lawn mowers.

Another way to approach this question is to set up the equation were X stands for the number of lawn mowers.

100 (3/X) = 0.06% which is a single variable algebraic equation.

47% out of 212,000 got it right.

Leave a Reply

Your email address will not be published.