Granny had 25 bananas.
2 answers:
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Answer:
(-0.1059 ; - 0.0337)
Step-by-step explanation:
The data table is attached in the picture below:
These is a matched pair design ; which requires taking the difference of the two values for each sample :
The mean and standard deviation of the difference will be used to construct the confidence interval :
The mean of difference, dbar = Σx/n = - 0.0698
The standard deviation of difference, Sd ;
Sd = [√Σ(d - dbar)²/(n-1)] = 0.1054
n = sample size = 25
The confidence interval :
dbar ± [TCritical * Sd/√n]
Tcritical at 90% ; df = n -1 = 25 -1
Tcritical(90% , 24) = 1.1711
C.I = - 0.0698 ± (1.711 * 0.1054/√25)
C.I = - 0.0698 ± 0.0361
C.I = (-0.1059 ; - 0.0337)
Answer:
95% of the population spent between 16.8 hours to 26.2 hours on social media per month
Step-by-step explanation:
- subtracting 1 from sample size: 83-1= 82
- Note Mean=21.5 and standard deviation=2.5
- Subtracting confidence interval from 1 and dividing by 2: (1-0.95)/2=0.025
- At α=0.025 and dF=82, the t-distribution table gives 1.984
- Divide standard deviation by square root of sample size: 21.5/√83= 2.36
- Multiplying answer in step 4 by answer in step 5: 2.36×1.984= 4.68
- For lower end: 21.5-4.68= 16.82
- for upper end: 21.5+4.68=26.18
