# Statistics

posted by .

The weight of adult green sea urchins are normally distributed with a mean 52g and standard deviation 17.2g?
A. Find the percentage of adult green sea urchins with weighs between 50g and 60g

My answer/work: normalcdf (50, 60, 52, 17.2) = .225, 23%

B. Obtain the percentage of adult green sea urchins with weights above 40g

My answer/work: normalcdf (40, e99, 52, 17.2) = .757, 76%

C. Determine and interpret the 90% percentile for the weights

My answer/work: invnorm: .9, 0,1) =1.28
z-52 + (1.28)*(17.2)
z= 74.04%

I'm a little unsure if I got C correct. As for the rest I'm wondering if I did them correctly. If not, could someone lean me to the right direction? Thank you :)

• Statistics -

A. Z = (score-mean)/SD

Z = (50-52)/17.2 = -2/17.2 = -.12

Z = (60-52)/17.2 = 8/17.2 = .47

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z scores.

.0478 +.1808 = .2286 = 23%

B. Similar process.

C. Correct

## Similar Questions

1. ### English

1. There are starfish, jellyfish, sea anemones, sea horses, sea urchins, etc in the ocean. 2. There are starfishes, jellyfishes, sea anemones, sea horses, sea urchins, etc in the ocean. (Which expression is correct?
2. ### statistics

Cholesterol levels of adult males are approximately normally distributed with a mean of mg/dL and a listed standard deviation of . Some researchers claim that the standard deviation of cholesterol levels of adult males is less than …
3. ### statistics

Cholesterol levels of adult males are approximately normally distributed with a mean of mg/dL and a listed standard deviation of . Some researchers claim that the standard deviation of cholesterol levels of adult males is less than …
4. ### Statistics

The weights of adult males are normally distributed with a mean of 172 lb and a standard deviation of 29 lb. 1.Find the weight that divides the upper 2% of weights from the lower 98%. Can anyone please explain how to do this,I have …
5. ### Statistics

The weights of adult males are normally distributed with a mean of 172 lb and a standard deviation of 29 lb Q.Find the weight that divides the upper 2% of weights from the lower 98%
6. ### statistics

The weights of a group of adult males are normally distributed with a mean of 180lb and standard deviation of 8lb. Find the probability that a randomly chosen male from this group weighs more than 190lb.
7. ### Statistics

assume that adults have IQ scores that are normally distributed with a mean of 105 and a standard deviation of 15 find the probability that a randomly selected adult has an IQ between 89 and 121 ?
8. ### statistics

adult males have normally distributed heights with mean of 69.0 in and a standard deviation of 2.8 in. if a clothing manufacture decides to produce goods that exclude the shortest 12% and the tallest 12% of adult males, find the minimum …
9. ### science

I have a question on homework. please help Sea otters are part of a giant kelp ecosystem. They feed on sea urchins that feed on kelp. How does hunting sea otters affect the population of sea urchins and kelp in the ecosystem?
10. ### Maths

2a) assume that adult males have footless which are normally distributed with mean 24.6 cm and standard deviation 1.05 cm. Calculate the probability that an adult male has a foot length is greater than 27 cm. My answer - 2 2b) assume …

More Similar Questions