A.91 is 3.5% of what number
1) Considering that 91 defective bolts correspond to 3.5% of the total sample.
2) So we can write out the following ratio:
Note that we have cross multiplied.
Since 100% is equivalent to the total number, thus we can state that 2600 bolts were inspected.
And the answer, since we need to reread it is in other words asking:
A.91 is 3.5% of what number