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Tutors Answer Your Questions about Describing-distributions-with-numbers (FREE)
Question 1198517: Scores for a common standardized college aptitude test are normally distributed with a mean of 518 and a standard deviation of 113. Randomly selected students are given a Test Preparation Course before taking this test. Assume, for sake of argument, that the preparation course has no effect.
If 1 student is randomly selected, find the probability that their score is at least 553.4.
P(X > 553.4) =
Enter your answer as a number accurate to 4 decimal places.
If 20 students are randomly selected, find the probability that their mean score is at least 553.4.
P(
¯¯¯
X
X
¯
> 553.4) =
Click here to see answer by ewatrrr(24785)   |
Question 1198939: Which of the following two sets of numbers is true of the center and spread?
a) 2,3,6,8,9
b) 4,5,7,8,9
One of the following is the correct answer. Which one?
A) the median is the same but set b has the larger IQR
B) the b set has the larger median and IQR
C) set b has the larger median and smaller IQR
D) the IQRs are the same but set b has the larger median.
Click here to see answer by MathLover1(20850)  |
Question 1201185: In the claims department of an insurance office various quantities are
computed at the end of each day’s business. On Monday, 20 claims are
received for a particular class of policy. The mean claim amount is calculated
to be K4,500 and the standard deviation to be K2,540. On Tuesday, the
claims are reviewed and one claim which was incorrectly recorded as K13,000
is now corrected to K3,000. Determine the mean and standard deviation of
the corrected set of claims
Click here to see answer by Theo(13342)  |
Question 1203964: The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.9 days and standard deviation of 1.3 days. Use your graphing calculator to answer the following questions. Write your answers in percent form. Round your answers to the nearest tenth of a percent.
a) What is the probability of spending less than 8 days in recovery?
b) What is the probability of spending more than 4 days in recovery?
c) What is the probability of spending between 4 days and 8 days in recovery?
Click here to see answer by ikleyn(52800)  |
Question 1204047: Potato chip lovers do not like soggy chips, so it is important to find characteristics of the production process that produces chips with an appealing texture.
The following sample data on the frying time (in seconds) and moisture content (%) of potato chips were collected:
Frying time (X) Moisture content (Y)
65 1.4
50 1.9
35 3
30 3.4
20 4.2
15 8.1
10 9.7
5 16.3
3.1 Draw a scatter diagram to represent the two variables.
3.2 Calculate the Pearson’s correlation coefficient.
3.3 Comment on the strength of the relationship between the two variables.
3.4 Determine the linear regression equation.
3.5 Estimate the moisture content of chips that were fried for 25 seconds.
Click here to see answer by Theo(13342) |
Question 1205250: The weights for newborn babies is approximately normally distributed with a mean of 6.5 pounds and a standard deviation of 1.8 pounds
Consider a group of 1300 newborn babies
1. How many would you expect to weigh between 3 and 7 pounds?
2. How many would you expect to weigh less than 6 pounds?
3. How many would you expect to weigh more than 4 pounds?
4. How many would you expect to weigh between 6.5 and 10 pounds?
Click here to see answer by MathLover1(20850) |
Question 1209043: Dave's GRE average score is 600 with standard deviation of 120 points. What is the standard score for a person who scores 730? Rita's GRE average score is 450 with standard deviation of 130 points. What is the standard score for a person who scores 720? Who did better on the GRE in terms of the mean?
Click here to see answer by ikleyn(52800) |
Question 1204046: The amount of caffeine in a sample of 250ml servings of brewed coffee is summarized in the table below:
Caffeine (mg) Number of cups
60 < 80 : 1
80 < 100 : 12
100 < 120 : 25
120 < 140 : 10
140 < 160 : 2
2.1 Calculate the average caffeine content of the 250ml cup
2.2 Calculate the modal caffeine content of the 250ml cup.
2.3 Calculate the median caffeine content of the 250ml cup.
2.4 Calculate the standard deviation of the content of the 250ml cup
Click here to see answer by ElectricPavlov(122) |
Question 1191145: Find some means. Suppose that X is a random variable with mean 20 and standard deviation 2. Also suppose that Y is a random variable with mean 40 and standard deviation 7. Assume that the correlation between X and Y is zero. Find the mean of the random variable Z for each of the following cases. Be sure to show your work.
A)Z=25−12X.
B)Z=13X−8.
C)Z=X+Y.
D)Z=X−Y.
E)Z=−3X+3Y
Click here to see answer by CPhill(1959)  |
Question 1190376: A graduate psychology student finds that 64% of all first semester calculus students in Prof. Mean’s
class have a working knowledge of the derivative by the end of the semester.
a) Take X = percentage of students who have a working knowledge of calculus after 1 semester,
and find a beta density function that models X, assuming that the performance of students in
Prof. Mean’s is average.
b) Find the median of X (rounded to two decimal places) and comment on any difference between
the median and the mean.
Density function of the β- distribution is given by
f(x) = (β + 1)(β + 2)x^β(1 − x); x ∈ [0; 1], β > 0
Click here to see answer by CPhill(1959) |
Question 1186302: A manufacturing company regularly conducts quality control
checks at specified periods on the products it manufactures.
Historically, the failure rate for LED light bulbs that the company
manufactures is 5%. Suppose a random sample of 10 LED light
bulbs is selected. What is the probability that
a. none of the LED light bulbs are defective?
b. exactly one of the LED light bulbs is defective?
c. two or fewer of the LED light bulbs are defective?
d. three or more of the LED light bulbs are defective?
Click here to see answer by CPhill(1959) |
Question 1178024: The final grade in statistics of 80 student at AAMUSTED Mathematics level100 are recorded below,
68 84 75 82 68 90 62 88 76 93
73 79 88 73 60 93 71 59 85 75
61 65 75 87 74 62 95 78 63 72
66 78 82 75 94 77 69 74 68 60
96 78 89 61 75 95 60 79 83 71
79 62 67 97 78 85 76 65 71 75
65 80 73 57 88 78 62 76 53 74
86 67 73 81 72 63 76 75 85 77
1:Using the sturge's approximation rule construct a frequency distribution table for the data above
2:Use the table to calculate;
* Mean and standard deviation
* Skewness and kurtosis.
Click here to see answer by CPhill(1959) |
Question 1174329: From past claims data for a particular insurance business, an insurance company considers that claims for the coming year will have a mean size of RM5000 and standard deviation of RM7500. Claim sizes are assumed to have a lognormal distribution. Estimate the probability of claims exceeding RM20000.
Click here to see answer by CPhill(1959) |
Question 1174328: In a survey of a company, mean salary of employees is MYR29,321 with standard deviation of MYR2,120. Consider the sample of 100 employees and find the probability their mean salary will be less than MYR29,000? (Hint: use central limit theorem).
Click here to see answer by CPhill(1959) |
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