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
-3 2/3 I just changed the mixed number into a improper fraction
Answer: the height in inches, of the pile after 3 weeks is 34 11/12 inches
Step-by-step explanation:
Each consecutive week for the next 5 weeks the height of pile increase by 8 7/12 inches. Converting 8 7/12 inches to improper fraction, it becomes 103/12 inches. The height is increasing in an arithmetic progression. The formula for determining the nth term of an arithmetic sequence is expressed as
Tn = a + (n - 1)d
Where
a represents the first term of the sequence.
d represents the common difference.
n represents the number of terms in the sequence.
From the information given,
a = 17 3/4= 71/4 inches
d = 103/12 inches
n = 3 weeks
the height in inches, of the pile after 3 weeks, T3. Therefore,
T3 = 71/4 + (3 - 1)103/12
T3 = 71/4 + 2 × 103/12 = 71/4 + 103/6
T3 = 419/12 inches = 34 11/12 inches