Saturday
December 7, 2013

# Posts by Rhea

Total # Posts: 55

Statistics
19. George got 70% on an economics exam where the mean was 55% and the variance was 9. If a professor wishes to change the distribution of marks so that they have a mean of 70% and a standard deviation of 5, what will George’s new mark be? a) 95% b) 85% c) 90% d) Over 100...

Statistics - M/C
14. The marks on a statistics test are normally distributed with a mean of 62 and a variance of 225. If the instructor wishes to assign B’s or higher to the top 30% of the students in the class, what mark is required to get a B or higher? a. 68.7 b. 71.5 c. 73.2 d. 74.6 e...

Statistics
The weather forecaster reports that the probability of rain tomorrow is 10%. a. Which approach was used to arrive at this number? Was it the analytical (classical) approach, relative frequency approach or subjective approach?

Statistics
Determine whether each of the following is a valid probability distribution. a) X: 0, 2, 2, 3 P(x): .1, .3, .4, .1 b) X: 5, -6, 10, 0 P(x): .01, .01, .01, .97 c) X: 14, 12, -7, 13 P(x): .25, .46, .04, .2

Statistics - M/C
The weather forecaster reports that the probability of rain tomorrow is 10%. a. Which approach was used to arrive at this number? 1) Analytical (Classical) 2) Relative Frequency 3) Subjective

Statistics
Is the following classified as interval, ordinal or nominal data? The marks achieved by the students in a statistics course out of 100.

Statistics
n=1000, bell-shaped Mean - 5,000 ~950 lie +/-100 of 5000 -4900 to 5100 Required 1) Standard Deviation 2) 97.5th percentile value 3) Z-score for 16th percentile

Check Statistics
Calculate the first, second, and third quartiles of the following sample. 2 2 3 3 4 4 4 5 5 5 7 7 8 9 10 Are my answers correct: 25th percentile = 3 50th percentile - 5 75th percentile = 7

Statistics
A statistics practitioner determined that the mean and standard deviation of a data set were 120and 30, respectively. What can you say about the proportions of observations that lie between each of the following intervals? a. 90 and 150 b. 60 and 180 c. 30 and 210

Statistics
A friend calculates a variance and reports that it is -25.0. How do you know that he has made a serious calculation error?

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