Confidence Intervals/Z-Score

A sample of 40 people owned an average of 1.35 apple products. It is known from a previous study that the population standard deviation of apple product ownership is 0.63 products. Construct a 95% confidence interval.

• (1.11, 1.58)
• (1.15, 1.55)
• (1.19, 1.51)
• (1.09, 1.61)

Tags

CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

CCSS.HSS.ID.A.4

The 90% interval for a statistics test was given by 72 +- 7. What is the lower value for the interval?

• 7
• 72
• 65
• 79

A random sample of 150 students has a grade point average with a mean of 2.86. Assume the population standard deviation is 0.78. Construct the confidence interval for the population mean if c = 98%.

• (2.51, 3.53)

• (2.43, 3.79)

• (2.31, 3.88)

• 2.71, 3.01)

In a survey of 2480 golfers, 15% said they were left-handed.  The survey's margin of error was 3%.  Construct a confidence interval for the proportion of left-handed golfers.

• (0.18, 0.21)
• (0.12, 0.18)
• (0.12, 0.15)
• (0.11, ).19)

Tags

CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

The standard IQ test has a mean of 96 and a standard deviation of 14.  We want to be 99% certain that we are within 4 IQ points of the true mean.  Determine the required sample size.

• 82
• 178
• 10
• 1

Construct a 95% confidence interval for the population mean mu. Assume the population has a normal distribution. A sample of 20 college students had mean annual earnings of $3120 with a standard deviation of $677. (Pick the best answer)

• ($2803, $3437)

• ($2135, $2567)

• ($2657, $2891)

• ($1324, $1567)

Construct a 95% confidence interval for the population mean, mu.  Assume the population has a normal distribution.  A sample of 25 randomly selected students has a mean test score of 81.5 with a standard deviation of 10.2

• (77.29, 85.71)
• (87.12, 98.32)
• (66.35, 69.89)
• (56.12, 78.34)

A random sample of 40 students has a test score with mean = 81.5.  Assume the population standard deviation is 10.2.  Construct the confidence interval for the population mean, mu, if c = 0.90.

• (78.8, 84.2)
• (66.3, 89.1)
• (51,8, 92.3)
• (71.8, 93.5)

Adam's Z-score on a test is +2.5.  What does this mean?

• He'd better start studying.
• He did better than EVERYONE.
• He scored 2.5 standard deviations above the average.
• He did terrible.

Tags

CCSS.HSS.ID.A.4

If Gonzalo's score is 87, the class average is 82, and the SD is 4, what is Gonzalo's Z-score?

• -1.25
• +1.25
• +1.20
• +1.02

Tags

CCSS.HSS.ID.A.4