Posted by **Jon** on Friday, February 22, 2008 at 6:43pm.

1)A bookshelf holds 4 mysteries, 3 biograpghies, 1 book of poetry, and 2 reference books. If a book is selected at random from the shelf, find the probability that the book selected is a biography or reference book.

A)1/2

B)1/6

C)5/6

D)3/50

I chose A

5 bio/reference/10 total books

1/2

2)Find the standard deviation of the data set to the nearest tenth. (21,13,18,16,13,35,12,8,15)

A)16.8

B)7.8

C)7.3

D)5.7

I chose C

mean = 21+13+18+16+13+35+12+8+15/9

16.8

variance = (21-16.8)^2 = 17.64...did that with the rest and added them to get sqrt 53.7

standard deviation = sqrt 53.7

= 7.3

3)Find the exact value of sin165

A)(sqrt6) - (sqrt2)/4

B)(sqrt6) + (sqrt2)/4

C)(sqrt2) - (sqrt6)/4

D)(sqrt of sqrt6 - sqrt2)/4

I chose A

(in D, there is a sqrt over both the sqrt6 and sqrt2

If I have it wrong can you explain how to do these types of problems b/c what I do is just take the sqrt of 6, subtract that from the sqrt of 2 and then divide by 4. I always end up with the same answer when I get the value of sin165 when I type it in my calculator

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