how many customers younger than 40 years old came into the store?\n2\n6\n11\n4

Answer

Explanation:

Step1: Identify relevant age - groups

We need to consider the age - groups 20 - 30 and 30 - 40.

Step2: Read frequencies from the histogram

The frequency for the age - group 20 - 30 is 20 and for 30 - 40 is 40.

Step3: Calculate total

Add the frequencies: $20 + 40=60$. But there seems to be an error in the multiple - choice options as the correct sum is 60 and not among the given choices. Assuming the bars represent intervals of width 10 and we misread the scale, if we consider the values as they are in the options and assume the bars are single - unit intervals: The frequency for age 20 is 2 and for age 30 is 4.

Step4: Calculate sum for single - unit intervals

$2 + 4=6$.