## hlpwntd 2 years ago i didnt ask any question i answered one :O

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1. hlpwntd

regression estimate = 15 the intervals in standard units are: -1.2815 < 80% > 1.2815 -1.96 < 95% > 1.96 regression estimate/rms error = 1.2815 score/rms error = 1.96

2. hlpwntd

not 24.7 here is a tip: score = regression estimate (score/rms error) / (regression estimate/rms error)

3. kropot72

If the scatter diagram is football-shaped, the r.m.s. error for the regression line can be used like a standard deviation for the regression line. 15 points correspond to a z-score of 1.2815. Therefore one standard deviation is 15/1.2815 = 11.7 points. About 95% of the points are within two r.m.s.errors from the regression line. For about 95% of the students, the regression estimate of final score based on midterm score is correct to within 2 * 11.7 = 23.4 points.

4. hlpwntd

kropot72, where do you get the 2 from in your 2 * 11.7 = 23.4 ?

5. kropot72

You could use 1.96 instead of 2. About 95% of the points are within 1.96 r.m.s.errors from the regression line.

6. hlpwntd

score = 15*1.96/1.2815 = 22.94

7. kropot72

For about 95% of the students, the regression estimate of final score based on midterm score is correct to within 23 points. Note that the question says " For about 95% of the students .......". Therefore an approximate rounded off answer is expected, in my opinion.

8. hlpwntd

a rounded answer would be 23, otherwise you would have to round all the other factors and denominators and it won't give u an accurate rounded answer an exact answer is the most approximatively correct answer :D

9. kropot72

So are you in doubt as to the value to put for the answer?

10. hlpwntd

nope id put 22.94 without a doubt an accurate answer is always the right 1, even with approximations. you can always round your answer if it is specifically required - just my opinion

11. kropot72

Not a problem with that. However the question itself is not precise when it states "For about 80% of the students ......" and "For about 95% of the students ......"

12. hlpwntd

imo 23.4 wouldn't work because rounding only 1 factor is wrong. here is why: - if you come with the right formula and your teacher can see that you came with the right 1 and rounded 1 factor on purpose, the answer would be correct, but it might be subject to your teacher's interpretation rather than vs your answer's raw accuracy - if you give an answer and the question doesn't require that you write the formula, the teacher has no way to accurately understand that you rounded 1 factor. your teacher's interpretation could be that you are wrong, even if your answer is actually right do i make sense ? :D

13. pandu

PROBLEM 2 Weights of male mountain lions follow the normal distribution with a median of 150 lb and an interquartile range of 8.2 lb. 2A : 2.0 POINTS Find the 75th percentile of the weights.