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3 years ago

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At a county concert the ratio of the number of boys to the number of girls is 2:7 if there are 250 more girls than boys how many

boys are at the concert?

1 answer:

kipiarov [429]3 years ago

8 0

For a 2:7 ratio there would be 100 boys and 350 girls

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A quality analyst of a tennis racquet manufacturing plant investigates if the length of a junior's tennis racquet conforms to th

Burka [1]

Answer:

Confidence interval : $21.506$ to $24.493$

Step-by-step explanation:

A quality analyst selects twenty racquets and obtains the following lengths:

21, 25, 23, 22, 24, 21, 25, 21, 23, 26, 21, 24, 22, 24, 23, 21, 21, 26, 23, 24

So, sample size = n =20

Now we are supposed to find Construct a 99.9% confidence interval for the mean length of all the junior's tennis racquets manufactured at this plant.

Since n < 30

So we will use t-distribution

Confidence level = 99.9%

Significance level = α = 0.001

Now calculate the sample mean

X=21, 25, 23, 22, 24, 21, 25, 21, 23, 26, 21, 24, 22, 24, 23, 21, 21, 26, 23, 24

Sample mean = $\bar{x}=\frac{\sum x}{n}$

Sample mean = $\bar{x}=\frac{21+25+23+22+24+21+25+21+23+ 26+ 21+24+22+ 24+23+21+ 21+ 26+23+ 24}{20}$

Sample mean = $\bar{x}=23$

Sample standard deviation = $\sqrt{\frac{\sum(x-\bar{x})^2}{n-1}}$

Sample standard deviation = $\sqrt{\frac{(21-23)^2+(25-23)^2+(23-23)^2+(22-23)^2+(24-23)^2+(21-23)^2+(25-23)^2+(21-23)^2+(23-23)^2+(26-23)^2+(21-23)^2+(24-23)^2+(22-23)^2+(24-23)^2+(23-23)^2+(21-23)^2+(21-23)^2+(26-23)^2+(23-23)^2+(24-23)^2}{20-1}}$

Sample standard deviation= s = $1.72$

Degree of freedom = n-1 = 20-1 -19

Critical value of t using the t-distribution table $t_{\frac{\alpha}{2}$ = 3.883

Formula of confidence interval : $\bar{x} \pm t_{\frac{\alpha}{2}} \times \frac{s}{\sqrt{n}}$

Substitute the values in the formula

Confidence interval : $23 \pm 1.73 \times \frac{1.72}{\sqrt{20}}$

Confidence interval : $23 -3.883 \times \frac{1.72}{\sqrt{20}}$ to $23 + 3.883 \times \frac{1.72}{\sqrt{20}}$

Confidence interval : $21.506$ to $24.493$

Hence Confidence interval : $21.506$ to $24.493$

3 0

3 years ago

Read 2 more answers

The ratio of the angles in a triangle is 3:10:7. what is the measure of the smallest angle?

STALIN [3.7K]

So add all of them and then see smallest one sorry if I'm wrong

3 0

4 years ago

Please help me write this equation

tatuchka [14]

The answer is, y = -1/3 - 3

5 0

3 years ago

Mathew is watching a car race on TV. His favorite car covered 10 laps of 3.6 miles each in 18 minutes. What is average speed of

Karo-lina-s [1.5K]

In the given question, all the necessary information's are already provided. Using these information's it is easy to find the average speed of the car in miles per hour. It is given that the car covers 10 laps in 18 minutes and each lap is 3.6 miles in length.
Total distance covered by the car = (10 * 3.6) miles
   = 36 miles
Now we have to convert the time from minutes to hours. So
18 minutes = 18/60 hours
   = 3/10 hours
Now we can easily calculate the average speed of the favorite car of Mathew.
Average Speed = 36 * (10/3) miles/hour
   = 120 miles/ hour

8 0

3 years ago

PLEASE HELP <br><br> I WILL BRAINLIEST !

jasenka [17]

Answer:

10 1/12

Step-by-step explanation:

In order to subtract fractions, you have to give them a common denominator.

18 1/2 can be rewritten as 18 6/12, as they are the same thing and 6/12 simplifies to 1/2. We make it 6/12 because we have to subtract it by 8 5/12, and the denominators are both 12.

So now we have 18 6/12 - 8 5/12, which gives us 10 1/12.

8 0

3 years ago