We would be looking at the first question all parts here as:
Q12) a) From standard normal tables, we have here:
P(Z < 0.385) = 0.65
Therefore, P(Z < 0.385) = 1 - 0.65 = 0.35
Therefore 0.385 is the required z score here which cuts off the top 35% of the normal curve.
b) From standard normal tables, we have here:
P(Z < -0.842) = 0.2
Therefore the cuttoff value here is computed as:
= Mean -0.842*Std Dev
= 75 -0.842*5
= 70.79
Therefore 70.79 is the required cutoff value here.
c) From standard normal tables, we have here:
P(Z < 0.674) = 0.75
Therefore, due to symmetry, we have here:
P(-0.674 < Z < 0.674) = 0.5
Therefore -0.674, 0.674 are the required z scores here which cut off the middle 50% of the normal curve here.
12-13 show work 12. Using a normal distribution and z score formula answer the following questions:...
12 and 13 12. Using a normal distribution and z score formula answer the following questions: a. Find the Z-score that cuts off the top 35% of the nornval curve b. Find the data value to the nearest whole number that cuts off the bottom 20% of the curve given that the mean is 75 and sample standard deviation is 5. c. Find the z scores that cut off the middle 50% of the normal curve. 13. This question is...
12. Using a normal distribution and z score formula answer the following questions: a. Find the Z-score that cuts off the top 35% of the nornval curve b. Find the data value to the nearest whole number that cuts off the bottom 20% of the curve given that the mean is 75 and sample standard deviation is 5. c. Find the z scores that cut off the middle 50% of the normal curve. 13. This question is worth 4 points...
12. Using a normal distribution and z score formula answer the following questions: a. Find the Z-score that cuts off the top 35% of the nornval curve b. Find the data value to the nearest whole number that cuts off the bottom 20% of the curve given that the mean is 75 and sample standard deviation is 5. c. Find the z scores that cut off the middle 50% of the normal curve.
13. This question is worth 4 points only. A statistics professor has surveyed 225 NCC students to determine the cost of their textbooks for the semester. He determined that the sample mean was $425 with a population standard deviation of $75 i) Determine the standard error of a 95% confidence interval Determine the 95% confidence interval (round to the nearest whole number) iii) Determine the 99% confidence interval (round to the nearerst whole #) ii)
13. This question is worth 4 points only. A statistics professor has surveyed 225 NCC students to determine the cost of their textbooks for the semester. He determined that the sample mean was $425 with a population standard deviation of $75 i) Determine the standard error of a 95% confidence interval ii) Determine the 95% confidence interval (round to the nearest whole number) iii) Determine the 99% confidence interval (round to the nearerst whole #)
13. This question is worth 4 points only. A statistics professor has surveyed 225 NCC students to determine the cost of their textbooks for the semester. He determined that the sample mean was $425 with a population standard deviation of $75 i) Determine the standard error of a 95% confidence interval ii) Determine the 95% confidence interval (round to the nearest whole number) iii) Determine the 99% confidence interval (round to the nearerst whole #)
11. Use the following table to answer the questions X Y 7 18 8 23 10 28 13 32 37 16 41 20 45 52 14 26 a. Make a scatterplot and determine the relationship between X and Y b. Find the linear regression equation Y' = (round a and b to the nearest hundredth ) c. Find r and r’ to the nearest hundredth d. Use the equation found in part b to determine X to the nearest whole...
The difference between the T distribution and the standard normal (z) distribution decreases as the degrees of freedom increase. True False When estimating the number of responses to be collected in order to achieve a desired margin of error on a proportion, what value should be used for the population proportion if no estimate is available? Enter your answer as a decimal to 2 decimal places. A population is believed to have a standard deviation of 23.1. An analyst wants...
7. Determine whether a normal distribution or a normal distribution or t distribution should be used or whether neither of should be used to construct a confidence interval for the mean. (Section 6.2) Circle the correct answer. in a random sample of 22 families, the mean weekly food expense was $95.60 with a sample standard deviation of $22.50. Assume the weekly food expense is normally distributed. A) Normal distribution B) t-distribution C) Neither For a sample of 20 IQ scores...
1) Given a standard normal distribution, find the probability of having a z score higher than 1.67 ```{r} ``` 2) Given that test scores for a class are normally distributed with a mean of 80 and variance 36, find the probability that a test score is lower than a 45. ```{r} ``` 3) Given a standard normal distribution, find the Z score associated with a probability of .888 ```{r} ``` 4) Find the Z score associated with the 33rd quantile...