Question

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 1

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