1. Assume the readings on thermometers are normally distributed with a mean of 0 degrees and a standard deviation of 1.00 degrees C. Find the probablity P(z< -2.19 or z> 2.19, where z is the reading in degrees.
The probability of a temperature reading outside this range is
P = 0.028524
4. A simple random sample of FICO credit rating
scores is obtained, and the scores are listed below. As of this writing, the mean
FICO score was reported to be 676. Assuming the standard deviation of all
FICO scores is known to be 58.2, use a 0.05 significance level to test the claim
that these sample FICO scores come from a population with a mean equal to 676.
714, 751, 663, 790, 818, 779, 697, 836, 751, 834, 693, 800
What is the values of the test statistic? Z=
The p value is?=
Reject or fail HO? Is it sufficient yes or no?
The sample mean is 760.5. This is 84.5 higher than the population mean of 676.
With 12 samples, the standard error is 58.2 / sqrt(12) = 16.8.
The z-score for the sample mean is 84.5 / 16.8 = 5.0295.
The probability associated this z-score is 2 x 10^-7.
HO is that the population mean is 676. Our sample mean is sufficiently different from this, at the 0.05 confidence level, so we can reject H0.
5.Assume the readings on thermometers are normally distributed with a mean of 0 degrees and a standard deviation of 1.00. Find the probability?
P(-2.26<z2.26)
P = 0.023821
6. Tests of older baseballs showed that when dropped 22 ft onto a concrete surface, they bounced an average of 239.3 cm. In a test of 50 new baseballs, the bounce heights had a mean of 232.7 cm. Assume that the standard deviation of bounce heights is 3.9 cm. Use a 0.01 significance level to test the claim that the new baseballs have bounce heights with a mean different from 239.3 cm. Are the new baseballs different?
What is the value of the test statistic? (round 2 decimal places as needed)
Identify the critical value of z=(round 2 decimal places as needed)
Z = 11.97
Zcritical = 2.58
New baseballs are significantly different.
Christine is currently taking college astronomy. The instructor often gives quizzes. On the
past seven quizzes, Christine got the following scores:
50, 18, 31.0, 25, 11, 46, 61
Find the standard deviation s.
a-10,368.0
b-31.0
c-8,366.3
d-18.3 ß correct answer
A person purchased a slot machine and tested it by playing it 1123 times. There are 10 different categories of outcomes, including no win, win jackpot, win with three bells and so on. When testing the claim that the observed outcomes agree with the expected frequencies, the author obtained a test statistic of X2=15.835. Use 0.10 significant level to test the claim that the actual outcome agree with the expected frequencies. Does the slot machine appear to be working as expected?
test statistic is=?
critical value is=?
p value=?
State the conclusion..
Reject or do not reject Ho. Does the slot machine appear or does not appear to be functioning.
Test statistic is the chi squared value (15.835)
Critical value for 0.10 = 14.68
P(15.835) = 0.0704
H0: there is no difference between this slot machine and a working slot machine.
Ha: the slot machine differs from a working machine.
P > Pcritical, so we fail to reject H0.
Conclusion: the slot machine appears to be working.