Question

Adult male heights are normally distributed with a mean of 70 inches and a standard deviation of 3 inches. The average basketball player is 79 inches tall. Approximately what percent of the adult male population is taller than the average basketball player?

0.13%

0.87%

49.87%

99.87%

Answer 1

@srossd can you help?

Answer 2

So, the average basketball player is 3 standard deviations above the mean. You can view here:
http://4.bp.blogspot.com/_5u1UHojRiJk/TEh9BHxxPUI/AAAAAAAAAIQ/DafeQNMYFoE/s1600/ztable.gif
That 99.87% of samples from a normal distribution are below that level (go down to Z=3.00 to see that). So, the answer is the complement, 0.13%.

Answer 3

thanks so much! I have 2 other problems just like this and then I'm all done, are you up for it?

Answer 4

Yeah, sure

Answer 5

1) A car is designed to last an average of 12 years with a standard deviation of 0.8 years. What is the probability that a car will last less than 10 years?

0.621%

6.21%

93.79%

99.379%

2) The ages of trees in a forest are normally distributed with a mean of 25 years and a standard deviation of 4. Approximately what percent of the trees are between 20 and 30 years old?

10.56%

68.32%

78.88%

89.44%

Answer 6

I think the first one is A, is that right?

Answer 7

1) So, you're 2/0.8 = 2.5 standard deviations below the mean. Using the same table as before, it's 0.62%.
2) We want to be within 1.2 standard deviations of the mean. Using the table, we see that 11.5% are above that level, and 11.5% are below that level, so that leaves 76.98%. I'm guessing they just used a slightly different table, so the answer is still C.

Answer 8

ooh, okay thank you :)

Answer 9

The first was correct! XD