Probability Question

Question

Two owners of a cattle ranch, Robert and Val, want to find the average weight for the ranch’s 200 cows. Instead of weighing all of the cows:

1. Robert weighs 25 cows and gets an average weight of 1,550 pounds (stdev = 50)
2. Val weighs 100 cows and gets an average weight of 1,380 pounds (stdev = 50)

What is Val’s margin of error, rounded to the nearest whole number? (The formula is 1.96 (std dev) / 

Answer 1

Plug into the formula: 1.96 (50)/ sqrt(100)