We have had a few questions about the second problem set. #3 First, assume this

Question

We have had a few questions about the second problem set.

#3

First, assume this distribution is normal. You need to use the numbers provided to calculate the mean and standard deviation, then you should be able to find the z-scores you need to solve the rest of the problem. Also, remember when you are asked for a proportion, you want to give a number that falls between 0 and 1 (i.e., your answer should be expressed as a decimal). Finally, on Table A, you may find a weird value next to the z-score of ".78." This is a typo. The value should be "28.23%" (as a proportion, that would be .2823).

#4

The original instructor that wrote this problem may have used a funny rounding method. If you work out the problem correctly, you should get an answer that is very close, but it may be off by about .01 or .02 from the closest answer listed. If it helps, consider this a new set of options:

A. 0.07

B. 0.11

C. 0.19

D. 0

Name(s) EDUC 15: Problem Set 2 This problem set is due in class on Tuesday, January 24. Legibly write your name (or your group member nam at the top of each page. Fill in your answers in the es) spaces provided. If need more room, attach and clearly label an extra sheet to you this document. When appropriate, show your work! 1. 4 points) In a statistica class with 136 students, the profes records how much sor money each student has intheir possession during the first class ofthe semester. The histogram shown below represents the data he collected. Amount of money on dollars) Which of the following description is are comect regarding theshape ofthe histogram Choose all that apply)? Skewed right D) An outlier is present. Skewed left Unimodal Symmetric 2. (5 points For the given frequency distribution, construct the relative frequency and the cumulative frequency round to two decimal places. BMI) for teachers frequency frequency 33.9389 Name(s) 3. (6 points, 2 each An industrial arts instructor has designed a test of mechanical aptitude MechA) and having investigated its properties, finds that students with scores lower than Stend to do poorly in the class. Those with scores higher than 12 excel Administering it to arandom sample of industrial artsstudents reveals the following For this question work out the problem on aseparate t paper and attach it here. Cleary label your work so that the answers correspond to the guestiona a. What proportion ofthe sample will fallinthe area ofthe distribution expected to do poorly round to two decimal places)? What proportion ofthe sample will fall inthe area ofthe distribution expected to c Ascore of 12 occurs at what percentile? approximately normal, with mean 4 and standard deviation 3.0 in. What is the probability that amale chosen atrandon has a height between 72 and 73 in? For this question workout the problem on aseparate sheet ofpaper and attach it here. Cleary label your work so that the amunrens correspond to the questions. A 0.08 B. 0.12 C. 0.20 D. 0 E 0.42

Explanation / Answer

1)1) it is skewed right as its tail is extended towards right side.

an outlier is present in bin 100-110

it is unimodel cause it has unique mode at 0-10 interval

therefore option A , D and E are correct.

2)

3) total 10 values are there; putting them in ascending order

a) as there are 2 values lower then 8

hence % of people who fall in area to do poorly =(2/10)*100 =20%

b) again there are 2 values are higher then 12.

hence % of people who fall in area to excel =(2/10)*100 =20%

c)as 12 is 8th value

hence percentile =(8/(n+1))*100 =(8/11)*100 =72.73%

4)from normal distribution Z =(X-mean)/std deviation

here mean =70.4 and std deviation =3

hence P(72<X<73) =P((72-70.4)/3<Z<(73-70.4)/3) =P(0.53<Z<0.87) =0.81-.70 =0.11

therefore option B is correct.

BMI Frequency(f) rel frequency=f/total f cum frequency 15-20.9 2 0.04 2 21-26.9 12 0.27 14 27-32.9 15 0.33 29 33-38.9 11 0.24 40 39-44.9 5 0.11 45 45

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