Answer:
(17.736 ; 21.139)
Step-by-step explanation:
Given the data:
22 14 25 15 19 15 17 21 15 16 23 16 29 21 22 21
Confidence interval ; (C. I) :
Mean ± Zcritical * σ/sqrt(n)
The mean value for the data:
Mean = Σx / n
n = 16
Σx = 311
Mean = 311 / 16 = 19.4375
Zcritical at 90% = 1.645
σ = sqrt[Σ(x - mean)² / n]
Using calculator :
σ = 4.138
19.4375 ± 1.645 * 4.138/sqrt(16)
19.4375 ± 1.645 * 4.138/4
19.4376 ± 1.7017525
Lower bound = 19.4376 - 1.7017525 = 17.736
Upper bound = 19.4376 + 1.7017525 = 21.139