Final answer:
To find the average weight of all the cows on the ranch, we can calculate a weighted average from Robert's and Valli's samples, resulting in an average weight of 1414 pounds per cow.
Step-by-step explanation:
To find the average weight of all the cows on Robert and Valli's ranch, we can use the weighted average formula because they have weighed different numbers of cows.
Robert weighs 25 cows with an average weight of 1550 pounds:
- 25 cows * 1550 pounds/cow = 38750 pounds total
Valli weighs 100 cows with an average weight of 1380 pounds:
- 100 cows * 1380 pounds/cow = 138000 pounds total
Together, they have:
- 25 cows (Robert) + 100 cows (Valli) = 125 cows
- 38750 pounds (Robert) + 138000 pounds (Valli) = 176750 pounds total
The overall average weight of the ranch is calculated as:
- 176750 pounds total / 125 cows = 1414 pounds per cow