Need Help on a couple questions!!!

#1
IQ test scores are normally distributed with a mean of 102 and a standard deviation of 18. An individual's IQ score is found to be 103. Find the z-score corresponding to this value.

Here are the answers I have gotten it down to... Someone please help me out.

-18.00
0.06
18.00
-0.06

Find the area under the standard normal curve between z = 1.5 and z = 2.5.


0.9332
0.9938
0.0606
0.9816



The probability that a tennis set will go to a tiebreaker is 19%. In 260 randomly selected tennis sets, what is the mean and the standard deviation of the number of tiebreakers?

mean: 49.4; standard deviation: 7.02851336
mean: 49.4; standard deviation: 6.32566202
mean: 46.8; standard deviation: 7.02851336
mean: 46.8; standard deviation: 6.32566202


The local lottery sets up a game wherein a player has a chance of collecting $750.
The player must choose a 3-digit number and if it matches, the player receives $750
It costs $1 to play the game.
What is the expected profit (or loss) for each player.
No words, if it's a loss of $0.02, write it as -$0.02
NOT loss of 2 cents.
The FORMAT that is expected :
$4.00, -$4.00 etc. (Neither of which is correct!)

I have no idea on this question!!
 

leo

New Member
#2
hi ryan,

answer to tennis is std dev = 6.325662 and mean = 49.40

mean = np = 260 * .19 = 49.40
std dev = sq root of n*p (1-p)
= sq root of (260)(.19)(1.19)
= 6.325662