Answer:
A)σ_M = 1.2634
B) CI = (36.564, 41.516)
C) σ_M = 0.1151
Step-by-step explanation:
A) Formula for standard error is;
σ_M = σ/√n
We are given;
Mean; x¯ = 39.04
Standard deviation; σ = 11.51
Sample size; n = 83
Thus;
Standard error; σ_M = 11.51/√83
σ_M = 1.2634
B) formula for confidence interval is;
CI = x¯ ± z(σ_M)
z is critical value
At 95% Confidence interval, z = 1.96
Thus;
CI = 39.04 ± 1.96(1.2634)
CI = (39.04 + 2.476) and (39.04 - 2.476)
CI = (36.564, 41.516)
C) sample size is now increased to 10000
Thus,standard error is calculated as;
σ_M = 11.51/√10000
σ_M = 0.1151