Answer:
see below
Step-by-step explanation:
There are 7 students between 120 and 124 so take the median of 122
Multiply the number of students by the median
7 * 122 =854
There are 8 students between 124 and 128 so take the median of 126
Multiply the number of students by the median
8 * 126 =1008
There are 13 students between 128 and 132 so take the median of 130
Multiply the number of students by the median
13 * 130 =1690
There are 9 students between 132 and 136 so take the median of 134
Multiply the number of students by the median
9 * 134=1206
There are 3 students between 136 and 140 so take the median of 138
Multiply the number of students by the median
3 * 138 =414
To find the mean, take the total weight and divide by the number of students
(854+1008+1690+1206+414) = 5172 lbs
7+8+13+9+3 = 40 students
5172/40 =129.3 lbs for the average
This is an estimate because we do not know that the number of students in each category will weight the median on average. We use the mean as an estimate of their weight. The median is the middle number of the category.
