Statistics Checkpoint

Trace the representation, diagnose a boundary failure, and reconstruct a changed case.

Get every question correct to pass this checkpoint. You can review feedback, revise your answers, and submit again.

1. Data [1,2,3] becomes [1,2,30]. Which measure changes less? Select one.

Select one answer.

Median Mean Neither changes Both change equally

2. A population [2,4] has mean 3. What is its population variance? Select one.

Select one answer.

3 2 0.5 1

3. Every observation is multiplied by 3. What happens to standard deviation? Select one.

Select one answer.

It is multiplied by 3 It is divided by 3 It is multiplied by 9 It is unchanged

4. What is the median of [8,1,5,2]?

5. Adding 100 to every observation has what effect on variance? Select one.

Select one answer.

Multiplies it by 100 Makes it zero Adds 100 No change

6. Data [1,3,5] has squared deviations summing to 8. What is its sample variance? Answer as a decimal.

7. For paired x=[1,2,3], y=[1,3,2], a developer sorts each list independently before correlation. What fails? Select one.

Select one answer.

Centering becomes impossible The lists no longer have equal length The sorting changes the observation pairs and invents a stronger relationship Correlation always requires reverse-sorted values

8. correlation([4,4,4],[1,2,3]) returns 0.0 in this exercise. How should it be interpreted? Select one.

Select one answer.

A policy sentinel because one centered norm is zero Proof the variables are independent Proof the constant column caused the varying one Evidence that the sample is Gaussian

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