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ankoles [38]
4 years ago
14

(21.23) A study of the effect of exposure to color (red or blue) on the ability to solve puzzles used 42 subjects. Half the subj

ects (21) were asked to solve a series of puzzles while in a red-colored environment. The other half (21) were asked to solve the same series of puzzles while in a blue-colored environment. The time taken to solve the puzzles was recorded for each subject. The 21 subjects in the red-colored environment had a mean time for solving the puzzles of 9.64 seconds with standard deviation 3.43; the 21 subjects in the blue-colored environment had a mean time of 15.84 seconds with standard deviation 8.65. The two-sample t statistic for comparing the population means has value
Mathematics
1 answer:
Cloud [144]4 years ago
7 0

Answer:

There is enough statistical evidence to say that the means are different.

Step-by-step explanation:

<em>The question is incomplete:</em>

<em>"The two-sample t statistic for comparing the population means has value (±0.001)."</em>

<em />

The null and alternative hypothesis are:

H_0: \mu_r-\mu_b=0\\\\H_1: \mu_r-\mu_b\neq0

The level of significance is assumed to be α=0.01.

The difference of the sample means is:

M_d=M_r-M_b=9.64-15.84=-6.20

The standard deviation for the difference of the means is:

s_d=\sqrt\frac{s_r^2+s_b^2}{n} } =\sqrt\frac{3.43^2+8.65^2}{21} }=\sqrt{\frac{85.59}{21} }=\sqrt{4.12} =2.03

Then, the t-statistic is:

t=\frac{M_d-(\mu_r-\mu_b)}{s_d} =\frac{-6.20-0}{2.03}= -3.05

The degrees of freedom are:

df=n_r+n_b-2=21+21-2=40

With 40 degrees of freedom the t-critial for a significance of α=0.01 is t=±2.705.

As the t-statistic lies in the rejection region, the effect is significant and the null hypothesis is rejected.

There is enough statistical evidence to say that the means are different.

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leonid [27]
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do you need an explanation as well?
6 0
2 years ago
Eva has £6.05 in her moneybox.
PIT_PIT [208]

Answer:

11 of 20p, 22 of 10p and 33 of 5p

Step-by-step explanation:

Eva has 20p, 10p and 5p coins, total of £6.05 = 605p

Let 20p=x, 10p=y, 5p=z

<u>Then</u>:

  • 20x + 10y + 5z = 605
  • y : x = 2 : 1 ⇒ x= y/2
  • y : z = 2 : 3 ⇒ z= 3y/2

<u>Rewriting the first equation considering next two:</u>

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<u>Answer:</u> 11 of 20p coins, 22 of 10p coins and 33 of 5p coins

3 0
3 years ago
What is the median of 7,3,4,7,5,6,5,5,4​
kolezko [41]

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Each car on a computer train holds 20 people. On a particular morning, 5 cars were 90% full and 3 cars were 65% full. If the peo
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Answer:

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Step-by-step explanation:

The computation of the number of cars to be filled is shown below:

A car that is 90% full and the total people is 20 so 90% would be

= (.90)(20)

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A car that is 65% full and the total people is 20 so 65% would be

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= 129

Now the number of cars to be filled is

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3 years ago
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