Question

For a biology lab experiment, you have to randomly select four mice. The mice to be chosen come from a population bred to weigh 30 grams, give or take 5 grams or so. The total weight T of the four mice will be___________ grams, give or take__________ grams or so. Use the Pythagorean property of standard errors.

Answer 1

120; 10

Explanation:

The total weight T of the four mice is simply the sum of each individual weight, assuming the mean value as true:

`T=30+30+30+30 = 120\ grams`

Pythagorean property of standard errors assumes that:

`SD^2(X)+SD^2(Y)=SD^2(X\pm Y)`

Therefore, the standard error of the total weight is:

`SD(T) = √(5^2+5^2+5^2+5^2)\\ SD(T) = 10\ grams`

The total weight T of the four mice will be 120 grams, give or take 10 grams or so.