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Tems11 [23]
3 years ago
7

A psychological researcher did a study with a sample of 84 boys and found that the meam length of time that they remained engage

d with a science exhibit at a museum was 107 second. assuming that from past studies it was known that the population standard deviation was 11.7
a) the best estimate for the population mean u is__

b) find the 99% confidence interval of mean length of time for a recent population

Please helppppppp

Mathematics
1 answer:
Varvara68 [4.7K]3 years ago
4 0
Sample size= n= 84
sample mean= x = 107 s
population standard deviation =σ= 11.7

As, population standard deviation is given so we use the estimate:
                             x(+/-) z(α/2)(σ/√n)

At 99% Confidence interval means significance level is α=1-0.99= 0.01
So,
α/2=0.005
Now, z at α/2=0.005 
z= 2.576
Now, by putting values 
                               107(+/-)((2.576)(11.7/√84)) 
              ( 107-((2.576)(11.7/√84)), 107+((2.576)(11.7/√84))  )    
               (103.7, 110.288)                      


                                         
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3 years ago
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Rachel has 60 scones. She sells them to Robbie, Cameron, Louis, Tom and Charlie in that order. Each customer buys more scones th
Korvikt [17]
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Let's use n for amount that each following customer increases.

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Cameron=x+n
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Charlie=x+n+n+n+n

We know that they bought total of 60 scones.
Robbie + Cameron + Louis + Tom + Charlie = 60
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We are also given this information:
(Robbie + Cameron) = 3/7 * (Louis + Tom + Charlie)
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Now we can solve for the amount for each customer.
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Answer:

Step-by-step explanation:

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Range of the function → y ≥ 1 Or [1, ∞)

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