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Andre45 [30]
3 years ago
12

Internet company Gurgle is carrying out testing on the efficiency of its search engine. A sample of 31 searches have been carrie

d out and the time taken to display the results has been recorded for each search. The mean search time for the sample was calculated as 0.2258 seconds. The standard deviation of the search times for the sample was calculated as 0.0188 seconds. The population standard deviation of search times is unknown.
1. Select all the techniques that are commonly used to construct a confidence interval for the mean when the population standard deviation (σ) is unknown:

a. Approximate the population standard deviation (σ) with the sample standard deviation (s)
b. Replace the sample size (n) with n-1
c. Decrease the confidence level to compensate for the increased margin of error
d. Approximate the standard normal distribution with the Student's t distribution

2. Calculate the upper and lower bounds of the 95% confidence interval for the mean search time for the Gurgle search engine.
Mathematics
1 answer:
Mrac [35]3 years ago
3 0

Answer:

d. Approximate the standard normal distribution with the Student's t distribution

(0.2199 ; 0.2327)

Step-by-step explanation:

Given that :

Sample size, n = 31

Sample mean, xbar = 0.2258

Sample standard deviation, s = 0.0188

Confidence interval (C. I) :

xbar ± margin of error

Margin of Error : Tcritical * s/sqrt(n)

Degree of freedom, df = n - 1 = 31 - 1 = 30

Tcritical value :

T0.05/2, 30 = 2.042

Margin of Error = 2.042 * 0.0188/sqrt(31)

Margin of Error = 0.0068949

C. I = 0.2258 ± 0.0068949

Lower boundary : (0.2258 - 0.006895) = 0.2189

Upper boundary : (0.2258 - 0.006895) = 0.2327

(0.2199 ; 0.2327)

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alukav5142 [94]

Answer:

C

Step-by-step explanation:

This question can simply be answered by the process of elimination. All of the other answers have numbers behind the first number of the decimal. when you are rounding to the nearest tenth, you will have no numbers behind the decimal except 1. They will look like this:

11.70

23.30

45.60

So, since we are looking for the nearest tenth, we would choose C because it is the only one that is rounded.

8 0
2 years ago
What is this fraction?
Galina-37 [17]
The answer to the question is d. irrational
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3 years ago
Need help with math homework
Nuetrik [128]

Answer:

c

Step-by-step explanation:

am not sure but I think its C am not shure

5 0
3 years ago
Find the Area Of each circle.
Levart [38]

The area of the circle A and B is 86.54 inches and 124.62 mm

According to the statement

we have given that the radius of the circle A and b and we have to find the area of the given circle.

So, we know that the

The area enclosed by a circle of radius r is πr².

So, For area of the circle

For condition A :

diameter = 10.5 inches

then radius = 5.25

Area = πr²

Area = 3.14*27.56

Area = 86.54 inches

Now, For condition B :

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Area = 3.14*39.69

Area = 124.62mm

So, The area of the circle A and B is 86.54 inches and 124.62 mm

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5 0
2 years ago
2( 4x + 2) = 4x - 12(x-1)​
aksik [14]

Answer:

x=\frac{1}{2}

Step-by-step explanation:

distribute 2 into (4x+2) and -12 into (x-1)

8x+4=4x-12x+12

combine like terms

8x+4=-8x+12

add -8x on both sides

8x+8x+4=12

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subtract 4 on both sides

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divide both sides by 16

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hope this helps

8 0
3 years ago
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