MT1 Solution A

# MT1 Solution A - Statistics 1 3-A, Fall 2009 Midterm O ne I...

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Statistics 13-A, Fall 2009 I Midterm One - Version A i You are allowed one standard-sized sheet of notes, front and back, And a calculator for the exam. i 1. (25 points) Let X - N(20,5) I ! I (a) (5 points each) Find the following probabilities i. P(X > 20) ii. P(X > 28) 7- 8- 2d - = 1.6 3- iii. P(X > 12) 12-20 - = -1. L] c; iv. P(12 < X < 28) -a ~(-/.L~I-c I 6) I J -1.6 0 1.6 , : 2 x 0, vqcz = 6. %70V (b) (5 points) Find the value x so that P(X < x) = 0.881

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2. (15 points, 5 points each) Use the following probability distribution of the number of dogs per household to answer the questions below. I Let A= {X 2 1) and B = > 2). I I X = number of dogs P(X) (a) Find P(A) P(B) I I 0 1 2 3+ 0.6 0.2 0.05 0.15 P(A)= 0.2 +a.o( to, 15' -0. I (b) Suppose we know a family has at least one dog. What is the proba- bility they have at least a second? - I I P( sib) = 0. Y = 'y. ----- - - P~A) a , - 2- I I (c) Are A and B independent? Show your work.
Le 3. (20 points) Twenty-mtudents were asked how long they spent studying for this exam. Their responses, in hours, are given below: (a) (10 points) Create the five-number summary for the above data set /IZhx: I6 (b) (5 points) Create a boxplot of the data (c) (5 points) Is the mean greater than, less than, or approximately equal - - to, the median?

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## This note was uploaded on 04/04/2011 for the course STA 13 taught by Professor Samaniego during the Fall '10 term at UC Davis.

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MT1 Solution A - Statistics 1 3-A, Fall 2009 Midterm O ne I...

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