So if the standard deviation is 6 bpm, and the mean = 180, then +1s = 186, +2s = 192, -1s = 174, -2s = 168
a. The % less than 187 are all, including and less than, +1s. So 50% + 34.1% (1s) = 84.1% of the puppies
b. The % between 170 and 187 would be between -1.5s and +1s. So (34.1% × 2) + (13.6/2) = 68.2% + 6.8% = 75% of the puppies
c. Since in a) we said that the % for less than 187 bpm was 84.1%, we just take that % of 500: .841×500 = 420.5, so we'd expect between 420 and 421 puppies
d. 10% of all.puppies will have a heart rate greater than? This is asking what deviation above the mean corresponds to 10%.
This will be around those above around +1.5s, so around 188 bpm
