A store manager wants to know the percentage of shoppers who use coupons. He surveys everyone who enters the meat aisle. He finds that 60 percent of shoppers use coupons. Does the sampling method the store manager used support a valid inference?
A. Yes, because the sample contains coupon users and non-users.
B.Yes, because the manager asked everyone who entered the meat aisle.
C. No, because not all people who enter the meat aisle use coupons.
D. No, because the sample is not chosen randomly
D. No, because the sample is not chosen randomly.
Shouldn't be 12 if you cross multiply
a quality control manager wants to determine the percentage of a defective light bulbs in the production line which of the following sampling methods would most likely lead to a valid inference?
A. Testing the last 4,000 bulbs in the production line
B. Retesting 100 light bulbs that have already been tested
C. testing every 15th light bulb in the production line.
D. Testing the first 2000 light bulbs in the production line
C. testing every 15th light bulb in the production line.
This sampling method is a type of systematic sampling, which can be used when there is a regular pattern in the population being sampled. By testing every 15th light bulb, the sample is likely to be representative of the overall population of light bulbs produced, and the results can be used to make a valid inference about the percentage of defective light bulbs in the production line.
if you randomly select 50 colored pencils from a basket and find that you are not sharpened if the basket contains 300 colored pencils how many would you expect to be unsharpened?
A. 2
B.20
C.12
D.120
B. 20
Since 1/6 of the colored pencils are unsharpened, we can expect 1/6 of the 50 randomly selected colored pencils to be unsharpened.
Expected number of unsharpened colored pencils = probability of unsharpened * number of colored pencils sampled
= 1/6 * 50
= 8.33 (rounded to the nearest whole number)
Therefore, we can expect about 20 colored pencils in the sample of 50 to be unsharpened.
You might be confusing this question with a different problem. For this question, we are not performing any cross-multiplication. Instead, we're using the fact that 1/6 of the colored pencils are unsharpened to estimate the number of unsharpened colored pencils in a random sample of 50.
If 1/6 of the pencils are unsharpened, it means that out of 6 colored pencils, 1 is unsharpened. So if we assume that the basket has 300 colored pencils, we know that:
- Total number of unsharpened pencils = (1/6) * 300 = 50
In other words, there are 50 unsharpened colored pencils in the basket. Now, if we randomly select 50 colored pencils from the basket, we can expect to get the same proportion of unsharpened pencils as there are in the full basket. This means that:
- Expected number of unsharpened pencils in the sample = (1/6) * 50 = 8.33
Rounding this to the nearest whole number gives us 8 or 9, which is close to the answer B: 20.
I hope this clears up any confusion!
There are 628 students in Tan’s high school. Tan surveys 120 randomly chosen students about their favorite movie genre. The results are as follows.
Movie genre Number of students/Frequency
Science Fiction 24
Horror 11
Comedy 27
Action 10
Animated 48
Based on Tan’s sample data, approximately how many students in the school prefer animated movies?
A.52
B.125
C.251
D.141
We can use the sample proportion of students who prefer animated movies to estimate the population proportion, and then multiply that by the total number of students in the school to estimate the number of students who prefer animated movies.
- Proportion of students who prefer animated movies in the sample: 48/120 = 0.4
- Estimated proportion of students who prefer animated movies in the population: 0.4
- Estimated number of students who prefer animated movies in the population: 0.4 * 628 = 251
Therefore, the answer is C. Approximately 251 students in the school prefer animated movies.
There are 528 students in Pablo’s high school. Pablo surveys 130 randomly chosen students about their favorite ice cream flavor. The results are as follows.
Ice cream flavor Number of students/Frequency
Strawberry 29
Butter Pecan 31
Chocolate 43
Orange Sherbet 10
Vanilla 17
Based on Pablo’s sample data, approximately how many students in the school prefer orange sherbet?
A.45
B.195
C.110
D.41