The mean weight of 75 2nd graders is 55.7 lbs and
the mean weight of 25 1st graders is 42.6 lb.
What is the mean weight of the 100 children
To find the mean weight of the 100 children, we can use the concept of weighted average.
Step 1: Multiply the number of students by their respective mean weight for each grade.
For the 2nd graders:
Number of students: 75
Mean weight: 55.7 lbs
Total weight of 2nd graders = 75 * 55.7 = 4177.5 lbs
For the 1st graders:
Number of students: 25
Mean weight: 42.6 lbs
Total weight of 1st graders = 25 * 42.6 = 1065 lbs
Step 2: Add the total weight of the different grades together.
Total weight of all children = Total weight of 2nd graders + Total weight of 1st graders
= 4177.5 lbs + 1065 lbs
= 5242.5 lbs
Step 3: Divide the total weight by the number of children.
Number of children = Number of 2nd graders + Number of 1st graders
= 75 + 25
= 100
Mean weight of the 100 children = Total weight of all children / Number of children
= 5242.5 lbs / 100
= 52.425 lbs
Therefore, the mean weight of the 100 children is 52.425 lbs.