Stat 112 Quiz

Ice cream sales for Sweet Cream Company over the past 5 days are $130.50, $111.90, $155.00, $140.42, and $160.25. Calculate the sample mean for ice cream sales.

• $141.03

• $139.61

• $138.62

• $135.01

For the Normal Distribution, all of these statistics are synonymous except for which?

• Mean

• Median

• Quartile 2

• Mode

Which of these statistics is resistant to outliers?

• IQR

• Mean

• Variance

• Range

If 25% of students performed better on an exam than you, you scored in the (blank) percentile.

• 25

• 50

• 75

• 100

Which of these is NOT an assumption needed for linear regression?

• Linear relationship between X and Y

• Both X and Y are discrete, quantitative variables

• Observations are independent of each other

• Variances are approximately equal across groups being compared

If the sample proportion from a random sample of 80 subjects is 50%, what is the standard deviation of the sampling distribution of the sample proportion?

• 0.25

• .003125

• 0.071

• 0.056

The means of 2 groups are being compared. The 95% confidence interval for the difference of means is [-0.25, 1.03]. Which TWO statements below are true?

• If a 90% interval was constructed, the interval would narrow

• There is no evidence the means significantly differ

• There is evidence the mean for group 2 is larger than for group 1

• With a larger sample size, the interval would widen

Which of these correlation coefficients indicates the strongest linear relationship?

• -1.05

• 1.8

• 0.75

• -0.80

Calculate the y-intercept of the regression line if (10,15) and (16,7) are two points on the line.

• 28.33

• -1.33

• -5.63

• 15.99

If a random sample is at least size 30, choose the 3 correct statements about the sample mean.

• The sample mean must be positive

• The sampling distribution is centered around the population median

• The sampling distribution is centered around the population mean

• The sample mean takes into account every individual observation