# StudentD

Most popular questions and responses by StudentD
1. ## Statistiscs

Students in the psychology department consume an average of 5 cups of coffee per day with a standard deviation of 1.75 cups. The number of cups of coffee consumed is normally distributed. • What proportion of students consume an amount equal to or less

2. ## statistics/ Help!-thanks!

The producers of a new toothpaste claim that it prevents more cavities than other brands of toothpaste. A random sample of 60 people use the new toothpaste for 6 months. The mean number of cavities at their next check up is 1.5. In the general population

3. ## statistics

In a psychology class of 100 students, test scores are normally distributed with a mean of 80 and a standard deviation of 5. Approximately what percentage of students have scores between 70 and 90? A. 68% B. 80% C. 95% D. 99%

4. ## Statistics

If weight in the general population is normally distributed with an average of 160 and a standard deviation of 20 pounds, what is the probability of selecting someone who weights 120 or less or 170 or more pounds?

5. ## Statistics

For a hypothetical normal distribution of test scores, approximately 95% fall between 38 and 62, 2.5% are below 38, and 2.5% are above 62. Given this information, (a) the mode=_____ and (b) the standard deviation=_____ Thanks in advance!

6. ## statistics

Faculty in the psychology department at APUS consume an average of 5 cups of coffee per day with a standard deviation of 1.5. The distribution is normal. How many cups of coffee would an individual at the 25th percentile drink per day? A. 4 B. 5 C. 6 D. 7

7. ## Statistics

If weight in the general population is normally distributed with an average of 160 and a standard deviation of 20 pounds, what is the probability of selecting someone who weights 120 or less or 170 or more pounds?

8. ## Statistics

Calculate the Pearson product-moment correlation for the data below. X 3 4 2 1 Y 5 5 3 4

9. ## statistics/ Help!

What is the probability of pulling a heart from a standard (52-card) deck of playing cards? A. .25 B. .50 C. .75 D. 1.0 Thanks very much!

1. ## Statistiscs

z = (6 - 5)/1.75 = 0.57 .2157+.50= 0.7157x100=71.57% i.e 71.57% In the second part, find z using a z-table for the 80th percentile. Plug into the formula, along with mean and standard deviation. Solve for x. z = (x - mean)/sd z (sd)= X-mean z (sd)+mean= X

posted on August 29, 2012
2. ## Statistics

Thanks. For the z scores I have: z = (120 - 160)/20 = -40/20=-2 z = (170 - 160)/20 = 10/20= 0.5 and the z table for 2 -(area between Mean and z) 0.47725, area beyond: 0.02275 For 0.5: 0.19146 and area beyond: 0.30854 What do I do after that, and which # I

posted on August 29, 2012
3. ## Statistics

Thank you very much! I am having real problems with that. Is that the formula that should be used: ơ=√∑ (x- µ)2/N ?

posted on August 29, 2012