Answer:
15 houses
Step-by-step explanation:
1/3 * 72 = 24
5/8 * 24 = 15
20( -1.5r + 0.75)
Multiply everything by 20
= -30r + 15
Mu=80, sigma=39, X=85
Z=(X-mu)/sigma = 5/39=0.128=0.13
P(X<=85)= 0.5517 (from Z-table)
so, P(X>85)=1-0.5517=0.4483 approx. thats 44.8% probability.