Question: A random sample of 81 students was tested for the problem solving approach skills. The variance of the scores obtained from the sample was found to be 144. Find the 80% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed. 2 < 179 ; 11 < σ < 13 2 < 179 ; 11 < σ < 13 2 < 184 ; 11 < σ < 14 2 < 184 ; 11 < σ < 14 Steps to derive 1 The problem is to find 80% confidence interval for the variance (σ2 ) and standard deviation (σ) for the score.2 n s 2 = 1443 Degrees of freedom, d.f n 4 For a 80% confidence interval, α 5 α 2 0 . 2 0 2 α 2 6 With d.f α c 2 (1 - α/2) = 64.278 and c 2 α/2 = 96.5787 The 80% confidence interval for variance is8 119 < σ2 < 1799 Therefore, we can be 80% confident that the true variance for the score is between 119 and 179.
10 The 80% confidence interval for standard deviation is11 11 < σ < 1312 Therefore, we can be 80% confident that the true standard deviation for the score is between 11 and 13.Hence the right answer is Option B Click Here To Go Back Identify an odd number... Identify the number that fits the blank to make the number sentence true... Which of the following is likely to be picked from the set shown?.. Identify an odd number from the set... Identify the number that fits the blank to make the number sentence true... Identify an even number... Which object can be picked from the set shown?.. Which number fits the blank to make the number sentence true?.. Identify the number that fits the blank to make the number sentence true... Which fruit is impossible to be picked from the collection shown?.. Which one is impossible to be picked from the collection?.. Which number fits the blank to make the number sentence true?.. Which one is likely to be picked from the set shown?.. Identify the number that fits the blank to make the number sentence true... Which number fits the blank to make the number sentence true?.. Which number fits the blank to make the number sentence true?.. From which plate is it likely to pick a banana?.. Identify the number that fits the blank to make the number sentence true... Which fruit is certain to be picked from Plate 2?.. Which number fits the blank to make the number sentence true?.. Which number fits the blank to make the number sentence true?.. Solve.. Solve.. Identify the number that fits the blank to make the number sentence true... Solve.. Which number fits the blank to make the number sentence true?.. Solve.. Solve.. How many ones does the picture show? Choose the correct number... Which number fits the blank to make the number sentence true?.. Solve.. Solve.. Solve.. Solve.. Identify the number that fits the blank to make the number sentence true... Solve.. Choose the model that represents the number 12... Solve.. Solve.. Identify the number that fits the blank to make the number sentence true... Solve.. Solve.. Solve.. Solve.. Solve.. Solve.. Identify the number that fits the blank to make the number sentence true... Count how many tens and ones. Identify the number... Solve.. Solve.. Which number fits the blank to make the number sentence true?.. Solve.. Solve.. Identify the model that represents the number 30... Solve.. Solve.. Which number fits the blank to make the number sentence true?.. Solve.. Solve.. From which plate is it impossible to pick an apple or a banana?.. Using the graph, find the sales needed to produce a profit of $450... Solve.. Identify the number that fits the blank to make the number sentence true... Solve.. Solve.. Solve.. Solve.. From which plate is it certain to pick a piece of watermelon?.. Solve.. Solve.. Solve.. Identify the number represented by the model... Solve.. Solve.. Solve.. Solve.. Which fruit is impossible to be picked from Plate 1 and Plate 3?.. Add:.. Solve.. Add: .. How many tens are there in the figure?.. Solve.. Solve.. From which bag can you certainly pick a flower?.. Solve.. Solve.. Solve.. How many tens?.. From which bag can you certainly pick a fish?.. Solve.. Dolly wants to distribute chocolates to 46 students in one grade and 35 students in anothe.. Solve.. Solve.. Mrs. Rose's class and Mr. John's class are going on a field trip. How many students are go.. Which one of these is mostly likely to be picked from the bag shown?.. Solve.. Dolly has 12 cookies and she bought 19 more cookies. How many cookies does she have now?.. Solve.. How many tens?.. Joe has 15 entry passes for a show and he bought 6 more passes. How many passes does he ha..
