Chapter 7 Section 2

A large candy machine has 45% orange candies. If you took an SRS of 25 candies (n = 25) what is the mean of the sampling proportion of orange candies?

• 0.25

• 0.55

• 0.45

• Cannot be determined without the standard deviation

A large candy machine has 45% orange candies. If you took an SRS of 25 candies (n = 25) what is the standard deviation of the sampling proportion of orange candies?

• 0.0995

• 0.0099

• 5

• 0.1342

A large candy machine has 45% orange candies. If you took an SRS of 25 candies (n = 25) is the large counts condition met?

• Yes, since 0.45 x 25 > 10

• No, since 0.45 x 25 > 10

• Yes, since 0.45 x 25 > 10 and 0.55 x 25 > 10

• Yes, since n > 10

• No, since n < 30

A flight had 76 passengers; 12 in first class and 64 in coach. The transportation safety agency (TSA) selected 10 passengers at random for a screening. P-hat is the proportion of first class passengers in the sample. Is the 10% condition for independence met?

• Yes, 10 less than 10% of all passengers

• No, 10 is more than 10% of 76 passengers

• Yes, as long as it was an SRS

A poll asked an SRS of 1,012 adults if they drink the milk in their cereal bowl once the cereal has been eaten. An industry spokesperson states that 70% of adults do drink the milk (assume the claim is correct). What is the standard deviation of the sampling distribution of the proportion of adults who drink the milk?

• 0.0263

• 0.4583

• 0.0002

• 0.0144

A poll asked an SRS of 1,012 adults if they drink the milk in their cereal bowl once the cereal has been eaten. An industry spokesperson states that 70% of adults do drink the milk (assume the claim is correct). What is the probability of getting a sample of 1,012 adults that had a proportion that drank the milk equal to 67% or less?

• 0.9814

• 0.0186

• 0.5000

• 0.6815

• 0.0358

A poll was taken of 1000 adults on how they voted on a recent ballot proposition. In the sample, 60% stated they voted yes and 40% stated they voted no. How big would the sample need to be to have a standard deviation of the sampling distribution to be 1/2 the value of the standard deviation of the original 1000 person sample?

• 2000

• 500

• 4000

• 3000

A large mail order company claims it delivers 90% of its orders on time. In an SRS of 100 orders, 86 were delivered on-time. What is the probability an SRS of 100 orders would have an on time rate of 86% or less if the company really does deliver 90% of its orders on-time?

• 0.09

• 0.04

• 0.15

• 0.01

A large mail order company claims it delivers 85% of its orders on time. In an SRS of 100 orders is the large counts condition met?

• Yes, 100 x 0.85 >= 10 and 100 x 0.15 >=10

• No, 100 x 0.15 < 30

• Yes, n =100 > 30

• No, 100 is less than 10% of all deliveries

Why do we randomly select our samples?

• for control
• reduce bias
• so we don't get the same answers from everyone
• to eliminate confounding results