In: Statistics and Probability
Wildlife biologists inspect 145 deer taken by hunters and find 26 of them carrying ticks that test positive for Lyme disease.
a) Create a 90% confidence interval for the percentage of deer that may carry such ticks.
(____%,_____%)
(Round to one decimal place as needed.)
Solution :
Given that,
n = 145
x = 26
Point estimate = sample proportion = = x / n = 16 / 145 = 0.179
1 - = 1 - 0.179 = 0 .821
At 90% confidence level the z is ,
= 1 - 90% = 1 - 0.90 = 0.10
/ 2 = 0.10 / 2 = 0.05
Z/2 = Z 0.05 = 1.645
Margin of error = E = Z / 2 * (( * (1 - )) / n)
= 1.645 * (((0.179 * 0.8/21) / 145)
= 0.052
A 90% confidence interval for population proportion p is ,
- E < p < + E
0.179 - 0.052< p < 0.179 + 0.52
0.127 < p < 0.231
(12.7% , 23.1%)