Question

A study of the effects of acid rain on trees in the Hopkins Forest shows that 25 of 100 trees sampled exhibited some sort of damage from acid rain. This rate seemed to be higher than the 15% quoted in a recentEnvironmetricsarticle on the average proportion of damaged trees in the Northeast. Does the sample suggest that trees in the Hopkins Forest are more susceptible than trees from the rest of the region

Answer 1

Answer:

Yes

Step-by-step explanation:

We can test this claim using the one proportion z test :

x = 25 ; n = 100

Phat = x / n = 25 / 100 = 0.25

H0 : P = 0.15

H0 : P > 0.15

The test statistic :

Z = (phat - p) ÷ √p(1-p)/n

Z = (0.25-0.15) ÷ √(0.15*0.85)/100

Z = 2.8

Using the Pvalue from Zscore calculator :

α = 0.05

Pvalue (Z < 2.8) =0.0026

Pvalue < α ; We reject the Null