Question

A baseball collector took inventory of all of his baseball cards along with the value of each card. The box plot represents the values of the cards in his collection.

What percentage of the baseball cards are valued at less than $45?


less than 25%

between 25% and 50%

between 50% and 75%

more than 75%

Answer 1

Answer: less than 25%

Explanation:

The box plot can be read as follows:

The first black dot is the minimum value.

The first half of the rectangle is the lower quartile.

The line that separates the two rectangles is the median.

The second half of the rectangle is the upper quartile

The final point is the maximum.

Knowing that each quartile represents about the 25% of the elements for the set, we can see that both lower and upper quartile (and the 25% of the elements that come after the upper quartile) cost more than $45.

Then we know that at least the (25% + 25% + 25%) = 75% of the cards in the collection cost more than $45.

And we also have elements that are not in the lower quartile that cost more than $45, but we can not determine the percentage that they represent.

So we can only conclude that more than the 75% of the collection costs more than $45.

Now we want to know the percentage of the baseball cards valued at less than $45.

So if more than 75% is valued at more than $45.

Then less than 25% is valued at less than $25.