An ecological group suspects tuna are consuming dangerous levels of copper in a region of the world. Dangerous levels of copper are classified when they reach beyond 5.7 parts per million. A random sample of 21 tunas in the region were tested and the data is shown in the stemplot.

Part A: What proportion of the tuna in the sample have dangerous levels of copper in their systems? (4 points)

Part B: Construct and interpret a 98% confidence interval for the mean copper levels of the tuna if the sample of 21 tuna has a mean copper level of 4.77 parts per million and standard deviation of 1.16 parts per million. (6 points)

Answer:

a. 5 out of 21

b. (4.1811, 5.3589) 

Step-by-step explanation:

a. We can see from the stem plot that 5 out of the 21 tunas have dangerous levels of copper in their system because the copper level reached over 5.7, and the problem states "Dangerous levels of copper are classified when they reach beyond 5.7 parts per million" 

b. How to find it on calculator 

Step 1: [stat] 

Step 2: go to [tests] 

Step 3: go down to [7: zinterval] 

Step 4: make sure input is on [stats] 

Step 5: input the following 

: 1.16 

X (with the line above it): 4.77 

n: 21 

c-level: .98  

The solution is :

A.) The required proportion is 5/21=0.2381

B.) 98% confidence the true copper level (in parts per million) lies in the interval (4.13, 5.41).

A standard deviation (or σ) is a measure of how dispersed the data is in relation to the mean. Low standard deviation means data are clustered around the mean, and high standard deviation indicates data are more spread out.

here, we have,

A) From the stem-leaf plot, we see that out of 21 tunas, 5 have dangerous levels of copper since the levels go beyond 5.7 parts per million. The required proportion is 5/21=0.2381

B) Given the sample mean is {x}=4.77, sample standard deviation s=1.16 and the sample size is n=21.

Since the population standard deviation is not known, we use t-distribution.

So the 98% CI for mean is

4.77 ± t{1-0.02 /2,20} x 1.16/sqrt(21) = (4.13, 5.41)}

We are sure with 98% confidence the true copper level (in parts per million) lies in the interval (4.13, 5.41)

Learn more about standard deviation here:

brainly.com/question/23907081

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