1. Entomologist Heinz Kaefer has a colony of bongo spiders in his lab. There are 1000 adult spiders in the colony, and their weights are normally distributed with mean 12 grams and standard deviation 2 grams. (a) If a spider weighs 15.6 grams, what is the standard score (z-score)?

(b) What is the standard score of a spider in this colony that weighs 10 grams?

(c) Look at your answers for a and b. When the value is greater than the mean, what is the sign of the standard score? What happens to the sign when the value becomes less than the mean?

(d) About what percent of spiders in the colony weigh between 10 grams and 14 grams?

(e) About how many spiders in the colony weigh more than 13 grams? Remember to calculate the number of spiders, not a %

(f) What percent of the spiders weigh less than 9 grams?
(g) What is the weight of a spider at the 90th percentile?
(h) What is the weight of at the 15th percentile?