Suppose that about 22% of those called will find an excuse (work, poor health, travel out of town, etc.) to avoid jury duty. If 11 people are called for jury duty, what is the average number of people that will be available to serve on the jury?

1 Answer
Jun 30, 2017

See a solution process below:


If 22% find an excuse, then 78% are available (10% - 22% = 78%).

The problem can then be restated as:

What is 78% of 11?

"Percent" or "%" means "out of 100" or "per 100", Therefore 78% can be written as #78/100#.

When dealing with percents the word "of" means "times" or "to multiply".

Finally, lets call the number we are looking for "n".
Putting this altogether we can write this equation and solve for #n# while keeping the equation balanced:

#n = 78/100 xx 11#

#n = 858/100#

#n = 8.58#

The average number of people who will be available will be #9# (This is 8.58 rounded to the nearest integer).