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photoshop1234 [79]

4 years ago

12

Working together, jo and ralph can do the garden chores in 6 hours. it takes jo twice as long as ralph to do the work alone. how

many hours does it take jo working alone?

1 answer:

creativ13 [48]4 years ago

3 0

Let's say Ralph can do the chores in h hours, and Jo in 2h. Then:
1/h+1/2h=1/6
6+3=h
h=9
Ralph takes 9 hours working alone; Jo takes 18 hours
☺☺☺☺

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Answer:

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Step-by-step explanation:

Data given and notation

$\bar X_{1}=1.83$ represent the mean in 1990

$\bar X_{2}=1.94$ represent the mean for 2005

$s_{1}=1.48$ represent the sample deviation for 1990

$s_{2}=1.62$ represent the sample standard deviation for 2005

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$n_{2}=180$ sample size for 2005

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We need to conduct a hypothesis in order to check if the means for the two groups are different, the system of hypothesis would be:

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Alternative hypothesis: $\mu_{1} \neq \mu_{2}$

Since we don't know the population deviations for each group, for this case is better apply a t test to compare means, and the statistic is given by:

$z=\frac{\bar X_{1}-\bar X_{2}}{\sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}}$ (1)

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Calculate the value of the test statistic for this hypothesis testing.

Since we have all the values we can replace in formula (1) like this:

$z=\frac{1.83-1.94}{\sqrt{\frac{1.48^2}{180}+\frac{1.62^2}{180}}}}=-0.673$

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Since is a bilateral test the p value would be:

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Based on the p-value, what is your conclusion?

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Step-by-step explanation:

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