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stira [4]
3 years ago
8

A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean

is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 9.1 hours.
Mathematics
1 answer:
djyliett [7]3 years ago
8 0

Answer:

The probability is 0.0069

Step-by-step explanation:

First thing to do here is to calculate the z-score

Mathematically;

z-score = (x-mean)/SD/√(n)

where x = 9.1 , mean = 8.4 , SD = 1.8 and n = 40

Plugging these values into the z-score equation, we have;

z-score = (9.1-8.4)/1.8/√(40) = 0.7/1.8/6.325 = 0.0615

Now, we check the standard normal table for P(z > 2.46) = 0.0069

You might be interested in
Find the probability that the person is frequently or occasionally involved in charity work.
Schach [20]
Given the table below which shows the result of a survey that asked 2,881 people whether they are involved in any type of charity work.

\begin{tabular}
{|c|c|c|c|c|c|}
 &Frequently&Occassionally&Not at all&Total\\[1ex]
Male&227&454&798&1,479\\
Female &205&450&747&1,402\\
Total&432&904&1,545&2,881
\end{tabular}

Part A:

If a person is chosen at random, the probability that the person is frequently or occassinally involved in charity work is given by

P(being \ frequently \ involved \ or \ being \ occassionally \ involved)\\ \\= \frac{432}{2881} + \frac{904}{2881} = \frac{1336}{2881}=\bold{0.464}



Part B:

If a person is chosen at random, the probability that the person is female or not involved in charity work at all is given by

P(being
 \ female \ or \ not \ being \ involved)\\ \\= 
\frac{1402}{2881} + \frac{1545}{2881}-\frac{747}{2881} = 
\frac{2200}{2881}=\bold{0.764}



Part C:

If a person is chosen at random, the probability that the person is male or frequently involved in charity work is given by

P(being
 \ male \ or \ being \ frequently \ involved)\\ \\= 
\frac{1479}{2881} + \frac{432}{2881}-\frac{227}{2881} = 
\frac{1684}{2881}=\bold{0.585}



Part D:

If a person is chosen at random, the probability that the person is female or not frequently involved in charity work is given by

P(being
 \ female \ or \ not \ being \ frequently \ involved)\\ \\= 
\frac{1402}{2881} + \frac{904}{2881} + \frac{1545}{2881}-\frac{450}{2881}-\frac{747}{2881} = 
\frac{2654}{2881}=\bold{0.921}



Part E:

The events "being female" and "being frequently involved in charity work" are not mutually exclusive because being a female does not prevent a person from being frequently involved in charity work.

Indeed from the table, there are 205 females who are frequently involved in charity work.

Therefore, the answer to the question is "No, because 205 females are frequently involved charity work".
4 0
2 years ago
What is the value of -4D^2+15D^2÷5 for D=1
lutik1710 [3]

Plug in D:

-4(1)^2 + 15(1)^2/5

-4 + 15 / 5

-4 + 3 = -1

6 0
3 years ago
Read 2 more answers
I WILL GIVE BRAINLIEST to who answers this question correctly.
Alborosie
You start counting from 0 onwards:

C = 6
D = 8

Then C x D = 48

So the product CxD is situated at 48 units from 0



4 0
3 years ago
The distance from Kenya's house to her job is 18 miles. One morning she left her house at 7:15 a.m. She traveled at the rate of
Snezhnost [94]

20 minutes = 1/3 of an hour

1/3 = 0.333

 1/3 x 45mph = 15, so she drove 15 miles at 45mph

18-15 = 3

3 miles/ 20 mph = 0.15 hours


0.333+0.15 = 0.483 hours total

0.483 x 60 = 28.98 so approximately 29 minutes total driving time

7:15 + 29 minutes is 7:44 am she arrived at work

8 0
3 years ago
This mapping shows a functional relationship.
Dmitriy789 [7]

Answer:

Step-by-step explanation:

3 0
3 years ago
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