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

    asked on August 28, 2012
  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

    asked on August 25, 2012
  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%

    asked on August 15, 2012
  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?

    asked on August 28, 2012
  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!

    asked on August 28, 2012
  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

    asked on August 15, 2012
  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?

    asked on August 28, 2012
  8. Statistics

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

    asked on August 28, 2012
  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!

    asked on August 21, 2012
  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