Question

step 2: calculate the sample standard deviation from the given sample. round to two decimal places

step 3: find the critical value that is used in confidence interval

step 4: construct 80% confidence interval. round to two decimal place

A survey of several 9 to 11 year olds recorded the following amounts spent on a trip to the mall: $24.73, $24.85, $22.86, $23.81, $21.31, $17.40 Construct the 80 % confidence interval for the average amount spent by 9 to 11 year olds on a trip to the mall. Assume the population is approximately normal. Copy Data Step 1 of 4: Calculate the sample mean for the given sample data. Round your answer to two decimal places. Answerſ How to Enter) 1 Point Tables Keypad Keyboard Shortcuts ev Nex

step 2: find the critical value. round to 3 decimal place

step 3: find the standard deviation of the paired differences

step 4:construct 99% confidence interval. round to one decimal place

Answer 1

Question 1

22.49	mean Data
2.82	std. dev.

Critical value  t(α/2, n-1) = t(0.2 /2, 6- 1 ) = 1.476

Confidence Interval
X̅ ± t(α/2, n-1) S/√(n)
t(α/2, n-1) = t(0.2 /2, 6- 1 ) = 1.476

80% confidence interval is ( 20.79 , 24.19 )

Question 2

d̅ = Σdi/n = -4 / 10 = - 0.4

S(d) = √(Σ (di - d̅)2 / n-1)
S(d) = √( 108.4 / 9) = 3.47

Critical value t(α/2) = t(0.01 /2) = 3.250

Confidence Interval :-
d̅ ± t(α/2, n-1) Sd / √(n)
t(α/2) = t(0.01 /2) = 3.250

99% confidence interval is ( - 4.0 , 3.2 )