Complete the solution of the equation find the value of y when x equals 1 9x + 7y=-12

The test scores on a 100-point test were recorded for 20 students:71 93 91 86 7573 86 82 76 5784 89 67 62 7277 68 65 75 84a. Can

Dafna11 [192]

Answer: a. Yes

b. mean = 76.65

standard deviation = 10.04

c. 76.65 ± 4.4

Step-by-step explanation:

a. Stem and leaf Plot shows the frequencies with which classes of value occur. To create this plot, we divide the set of numbers into 2 columns: stem, the left column, which contains the tens digits; leaf, the right column, which contains the unit digits.

Normal distribution is a type of distribution: it's a bell-shaped, symmetrical, unimodal distribution.

A stem and leaf plot displays the main features of the distribution. If turned on its side, we can see the shape of the data.

The figure below shows the stem and leaf plot of the 100-point test score. As we can see, when turned, the plot resembles bell-shaped distribution. So, this test scores were selected from a normal population.

b. Mean is the average number of a data set. It is calculated as the sum of all the data divided by the quantity the sample has:

mean = $\frac{\Sigma x}{n}$

For the 100-point test score:

mean = $\frac{71+93+91+...+65+75+84}{20}$

mean = 76.65

Standard Deviation determines how much the data is dispersed from the mean. It is calculated as:

$s=\sqrt{\frac{\Sigma (x-mean)^{2}}{n-1} }$

For the 100-point test score:

$s=\sqrt{\frac{[(71-76.65)+(93-76.65)+...+(84-76.65)]^{2}}{20-1} }$

s = 10.04

The mean and standard deviation of the scores are 76.65 and 10.04, respectively.

c. Confidence Interval is a range of values we are confident the real mean lies.

The calculations for the confidence interval is

mean ± $z\frac{s}{\sqrt{n} }$

where

z is the z-score for the 95% confidence interval, which is equal 1.96

Calculating interval

76.65 ± $1.96.\frac{10.04}{\sqrt{20} }$

76.65 ± 4.4

The 95% confidence interval for the average test score in the population of students is between 72.25 and 81.05.

7 0

3 years ago

What is the circumference of a circle with a diameter of 13 inches? round to the nearest hundredth.

Kryger [21]

Answer:

40.84 to nearest hundredth.

Step-by-step explanation:

C = pi * d

= pi * 13

= 40.8407

7 0

3 years ago

A ski lift makes a 35° angle of elevation with the ground and takes passengers on a 6,550-foot ride up a mountain. Charlotte nee

Nesterboy [21]

Answer:

sin 35* x/6550

hypotenuse is 6550

35* left to the right angle

x above right angle

Step-by-step explanation:

Got lucky

4 0

2 years ago

a boat salesperson earns a 2.5% commission on the sale of each boat Find the commision earned on a boat that sells for 18,500

marin [14]

100% = 1.0
2.5% = 0.025

So now we know the decimal that corresponds to 2.5%, so all we have to do is multiply the price of the boat by this value in order to find the commission earned:

18 500 x 0.025 = $462.50

5 0

3 years ago

Read 2 more answers

PLEASE HELP ME PLEASE LOOK AT THE PICTURE I NEED AN ANSWER ASAP

Anvisha [2.4K]

Answer:

1st one is 2. 2nd one is 5. 3rd one is less than. 4th one is, is smaller

Step-by-step explanation:

5 0

3 years ago