Question 1157874: Trees planted by a landscaping firm have a 90% one-year survival rate. If they plant 12 trees in a park, what is the following probabilities:
1. All the trees survive one year.
2. At least 10 trees survive one year.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! 1. this has .90^12 probability or 0.2824
2. this means 10,11,or 12 trees survive
Can use the calculator or do it by hand for 10 and 11
for 10 it is 12C10^0.9^10*0.1^2=0.2301
for 11 It is 12*.9^11*.1=0.3766
the sum of those three is 0.8891
calculator do 1-binomcdf(12,.9,9), the calculator can only do the left side of the binomial, which isn't what we want. We find the cumulative probability of 0 to 9 trees and subtract that from 1 to get the probability we want,.
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