Stat Exam 2 Poll Questions

bills dad gives him allowance every week depending on his mood. 40% of the time he gives him $10, 30% of the time he gives him $20, 20% of the time he gives him $30, and 10% of the time he gives him $50. what is bills expected allowance?

$21

it is know that 70% of Americans have at least one credit card. a sample of 50 Americans is taken. calculate the probability that 30 or fewer people in this sample will have at least one credit card

.6-.7/square root (.7(.3)/50)= -1.54 -> 1-z(-1.54)= 0.0618

it is know that 70% of Americans have at least one credit card. a sample of 50 Americans is taken. how many people in the sample are expected to have at least one credit card

.7 * 50 = 35

the weight distribution of en is skewed due to some very heavy men. the population has mean 185 with standard deviation 15. a sample of 40 men was taken. what is the probability that the average weight for this sample is less than 180

0.0174

it is known that 70% of Americans have at least one credit card. a sample of 50 Americans is taken. calculate the standard error of the sampling distribution

0.0648

in a group of 12 clemson students, there are 5 from South Carolina, 4 from New Jersey, and 3 from Georgia. if 2 students are randomly selected from this group, what is the probability that both students are from the same state?

0.288 (5/12 * 4/11) + (4/12 * 3/11) + (3/12 * 2/11)

in 2020 the average SAT score was 1051 and the std was 108. sat scores are normally distributed. the top 10% of test takers in 2020 scored above x. calculate x

1189

mr Jenkins is running for county council for the very first time. how many voters need to be surveyed to estimate his support to within 5 percentage points with 99% confidence

664

the height distribution of men is normally distributed with mean 70 inches and standard deviation 3 inches. a sample of 16 men was taken. what is the probability that the mean of this sample is greater than 71.5 inches?

71.5-70/ 3/square root 16 = 2.0 -> 1- 0.9772= 0.0228

in 2016 it was found that 32.7% of frendhc people smoke. how many people would need to be surveyed in 2022 to determine the smoking rate within 3 percentage points with 95% confidence interval

940 (ROUND UP)

the weight of carving pumpkins is normally distributed with mean 15 pounds and standard deviation 1.2 pounds. the smallest 4% of carving pumpkins will be sold at a lower price. what is the cutoff weight for being reclassified and sold at a lower price

x=mu + z*theta = 15 + (z score of 0.04)(1.2) =12.9

the weight of carving pumpkins is normally distributed with mean 15 pounds and standard deviation 1.2 pounds. what weight represents the 90th percentile

x=mu + z*theta = 15 + (z score of 0.900)(1.2) = 16.536

if the normal probability plot is fairly linear and data don't fall outside confidence bands, we can assume the data is from

a normal population

which statement about the probability distribution is true x: -2. 1. 3. 7 p(x). .32. .28. .15. .25 a) e(x)= 1.84 b) the distribution is invalid because one value of x is negative c) p(x<1)= .60 d) all of the above are true

a) e(x)= 1.84

the weight distribution of men is skewed right due to some heavy men. the population has a mean of 185 lbs and standard devaition of 15. a sample of 40 men was taken. describe the sampling distribution of the sample mean.

approximately normal with means 185 and standard error 2.37

Scores on the SAT are Normally distributed, with a mean of 1060 and a standard deviation of 210. what value is closest to the SAT score that represents the upper quartile. a) 920 b) 1200 c) 1220 d) 1310

b) 1200 z<0.75= 0.67 x= mu + z*theta = 1060 + 0.67*210= 1200.7

which of the following is the best interpretation of billys allowance? the expected value is $21. a) every week bills dad gives him $21 b) over the course of several years, billy receives and average $21 c) the average allowance billy and all his siblings received is $21 d) if there are 5 weeks in a month then bills would receive $105 in allowance that month

b) over the course of several years, billy receives and average $21

it is known that 70% of Americans have at least one credit card. is a as maple size of 50 large enough for the sampling distribution of p^ to be normal? a) no since np(1-p)>=10 b) yes since np(1-p)>=10 c) no since n>=30 d) yes since n>=30

b) yes since np(1-p)>=10

what is the best indicator that the small sample came form a normal population: a) the histogram is basically bell shaped b) the histogram is unimodal c) the normal probability plot is basically linear d) the normal probability plot is basically bell shaped

c) the normal probability plot is basically linear

which statement is false? a) the number of marbles in a jar is discrete b) the weight of water in a jug is continuous c)the distance to myrtle beach is discrete d) the amount of time spent studying for a test is continuous

c)the distance to myrtle beach is discrete

the height distribution of men is normally distributed with mean 70 inches and standard deviation 3 inches. a sample of 16 men was taken. describe the sampling distribution of the sample mean x bar. a) distribution is unknown, mean is 70, std is 3 b) distribution is unknown, mean is 70, std is 0.75 c) distribution is normal, mean is 70, std is 3 d) distribution is normal, mean is 70, std is 0.75

d) distribution is normal, mean is 70, std is 0.75

which statement is grammatically correct? a) do you see how much people are here? b) can you believe the amount of people here? c) I thought there would be less people here than this! d) none of the above is correct e) all of the above is correct

d) none of the above is correct

the weight of carving pumpkins is normally distributed with mean 15 pounds and standard deviation 1.2 pounds. what is the probability that a randomly selected car ing pumpkin will weigh between 13.5 and 16.5 pounds

find z scores of 13.5 and 16.5 and subtract them p(-1.25<z<1.25)= .8944-.1056= .7888

what actions make the confidence interval wider

increase in the confidence level and a decrease in the sample size

increasing the sample size makes the confidence interval __

narrower

each student in a random sample of 200 students was asked if thei=y have a credit card. 136 said yes. calculate a point estimate with the right notation

p^= 0.68

np(1-p) deal with __ data

qualitative

n>=30 deals with __ data

quantitative