Answer:
17.1≤x≤23.1
Step-by-step explanation:
The formula for calculating the confidence interval is expressed as;
CI = x ± z*s/√n
x is the mean yield = 20.1
z is the 80% z-score = 1.282
s is the standard deviation = 7.66
n is the sample size = 11
Substitute
CI = 20.1 ± 1.282*7.66/√11
CI = 20.1 ± 1.282*7.66/3.3166
CI = 20.1 ± 1.282*2.3095
CI = 20.1 ±2.9609
CI = (20.1-2.9609, 20.1+2.9609)
CI = (17.139, 23.0609)
hence the required confidence interval to 1dp is 17.1≤x≤23.1
