The marks obtained by students are 10, 13, 12, 15, 25, 30, 20, 35, 40, 18. Calculate the median mark.

The spray from a spinning lawn sprinkler covers an area of 625pi square feet.

kari74 [83]

x/900(pi) = 135/360

x = [900pi][135/360] = 337.5(pi) sq ft (area that receives water)
Hope this helps!
~{Oh Mrs.Believer}

6 0

3 years ago

The mean number of words per minute (WPM) read by sixth graders is 8888 with a standard deviation of 1414 WPM. If 137137 sixth g

Bingel [31]

Noticing that there is a pattern of repetition in the question (the numbers are repeated twice), we are assuming that the mean number of words per minute is 88, the standard deviation is of 14 WPM, as well as the number of sixth graders is 137, and that there is a need to estimate the probability that the sample mean would be greater than 89.87.

Answer:

"The probability that the sample mean would be greater than 89.87 WPM" is about $\\ P(z>1.56) = 0.0594$ .

Step-by-step explanation:

This is a problem of the distribution of sample means. Roughly speaking, we have the probability distribution of samples obtained from the same population. Each sample mean is an estimation of the population mean, and we know that this distribution behaves normally for samples sizes equal or greater than 30 $\\ n \geq 30$ . Mathematically

$\\ \overline{X} \sim N(\mu, \frac{\sigma}{\sqrt{n}})$ [1]

In words, the latter distribution has a mean that equals the population mean, and a standard deviation that also equals the population standard deviation divided by the square root of the sample size.

Moreover, we know that the variable Z follows a normal standard distribution, i.e., a normal distribution that has a population mean $\\ \mu = 0$ and a population standard deviation $\\ \sigma = 1$ .

$\\ Z = \frac{\overline{X} - \mu}{\frac{\sigma}{\sqrt{n}}}$ [2]

From the question, we know that

The population mean is $\\ \mu = 88$ WPM
The population standard deviation is $\\ \sigma = 14$ WPM

We also know the size of the sample for this case: $\\ n = 137$ sixth graders.

We need to estimate the probability that a sample mean being greater than $\\ \overline{X} = 89.87$ WPM in the distribution of sample means. We can use the formula [2] to find this question.

The probability that the sample mean would be greater than 89.87 WPM

$\\ Z = \frac{\overline{X} - \mu}{\frac{\sigma}{\sqrt{n}}}$

$\\ Z = \frac{89.87 - 88}{\frac{14}{\sqrt{137}}}$

$\\ Z = \frac{1.87}{\frac{14}{\sqrt{137}}}$

$\\ Z = 1.5634 \approx 1.56$

This is a standardized value and it tells us that the sample with mean 89.87 is 1.56 standard deviations above the mean of the sampling distribution.

We can consult the probability of P(z<1.56) in any cumulative standard normal table available in Statistics books or on the Internet. Of course, this probability is the same that $\\ P(\overline{X} < 89.87)$ . Then

$\\ P(z$

However, we are looking for P(z>1.56), which is the complement probability of the previous probability. Therefore

$\\ P(z>1.56) = 1 - P(z$

$\\ P(z>1.56) = P(\overline{X}>89.87) = 0.0594$

Thus, "The probability that the sample mean would be greater than 89.87 WPM" is about $\\ P(z>1.56) = 0.0594$ .

5 0

3 years ago

A basketball court is 94 feet by 50 feet. Eight fans ca

IgorC [24]

Answer:

The entire floor can contain approximately 4178 fans

Step-by-step explanation:

The first step is to calculate the area of the basketball floor.

we can do this by multiplying the length by the breadth as such 94 X 50 = 4700 square feet.

The second step is to calculate the area occupied by 8 of the fans. We can do this by multiplying 3 ft by 3ft = 9 square feet.

From this, it will be easier to estimate the area occupied by only one fan. This can be got by dividing 9 square feet by 8.

This is = 1.125 square feet.

To get the number of students it can occupy, we divide the total area of the court by the area occupied by one student.

4700/ 1.125 =4177.8 $\approx$ 4178 fans

4 0

3 years ago

In London today, four times the high temperature was more than twice the high temperature plus

4vir4ik [10]

Answer:

Let's define the high temperature as T.

We know that:

"four times T, was more than 2*T plus 66°C"

(i assume that the temperature is in °C)

We can write this inequality as:

4*T > 2*T + 66°C

Now we just need to solve this for T.

subtracting 2*T in both sides, we get:

4*T - 2*T > 2*T + 66°C - 2*T

2*T > 66°C

Now we can divide both sides by 2:

2*T/2 > 66°C/2

T > 33°C

So T was larger than 33°C

Notice that T = 33°C is not a solution of the inequality, then we should use the symbol ( for the set notation.

Then the range of possible temperatures is:

(33°C, ...)

Where we do not have an upper limit, so we could write this as:

(33°C, ∞°C)

(ignoring the fact that ∞°C is something impossible because it means infinite energy, but for the given problem it works)

4 0

3 years ago

45 + 57 = x + y x= 37 y =?

Mekhanik [1.2K]

Answer:

y = 65

Step-by-step explanation:

45 + 57 = x + y

x = 37

45 + 57 = 37 + y

45 + 57 = 102

102 = 37 + y

-37 -37

102 - 37 = 65

37 + y - 37 = y

65 = y

y = 65

5 0

3 years ago

Read 2 more answers

The marks obtained by students are 10, 13, 12, 15, 25, 30, 20, 35, 40, 18. Calculate the median mark. ​

The marks obtained by students are 10, 13, 12, 15, 25, 30, 20, 35, 40, 18. Calculate the median mark.