Find the value of y. A. 18 B. 22 C. 24 D. 28

SAT reading and writing section scores of a random sample of twenty 11th-grade students in a certain high school are given below

kvasek [131]

Answer:

The value of test statistics is 25.

Step-by-step explanation:

We are given below the SAT reading and writing section scores of a random sample of twenty 11th-grade students in a certain high school;

380, 520, 480, 510, 560, 630, 670, 490, 500, 550, 400, 350, 440, 490, 620, 660, 700, 730, 740, 560

Let $\sigma$ = population standard of the reading and writing section SAT score of the students in this school

So, Null Hypothesis, $H_0$ : $\sigma \leq$ 100 {means that the reading and writing section SAT score of the students in this school is lesser than or equal to 100}

Alternate Hypothesis, $H_A$ : $\sigma$ > 100 {means that the reading and writing section SAT score of the students in this school is higher than 100}

The test statistics that would be used here is One-sample Chi-square test statistics;

T.S. = $\frac{(n-1)s^{2} }{\sigma^{2} }$ ~ $\chi^{2} __n_-_1$

where, $s^{2}$ = sample variance = $\frac{\sum (X-\bar X)^{2} }{n-1}$ = 13135.8

n = sample of 11th-grade students = 20

So, the test statistics = $\frac{(20-1)\times 13135.8^{2} }{100^{2} }$

= 24.96 ≈ 25

Hence, the value of test statistics is 25.

5 0

3 years ago

Doreen schmidt is a chemist. She needs to prepare 36 ounces of a 10% shydrochloric acid solution. Find the amount of 18% solutio

emmainna [20.7K]

Total = 36oz
Amount of 18% solution = x
Amount of 9% solution = 36 - x

Using the fact that (amount of solution) * (percent HCl) = amount HCl we can set up an expression for the amount HCl in a mixture of 18% and 9% solutions with a total volume of 36oz.

Amount of HCl = x*0.18 + (36 - x)*0.09

If we divide this by the amount of solution we get percent HCl, and we have a target of 10% HCl. Now we have an equation to solve,

[x*0.18 + (36 - x)*0.09]/36 = 0.1

x*0.09 + 3.24 = 3.6

.09x = 0.36
x = 4

Therefore,
4 ounces of 18% HCl solution and 32 ounces of 9% HCl solution

Check:
[(4*.18) + (.09*32)]/36 = 0.1?
0.1 = 0.1 Yes.

5 0

3 years ago

Please help me out i will mark brainliest i need help on this! Its plot dot and dot plotting!

finlep [7]

Answer:

b

Step-by-step explanation:

the second one it should be hope's it helps

5 0

2 years ago

a field in the shape of a trapezoid has an area of 13,687.5 square yards .the length of one base is 150yards, and the lenght of

Leviafan [203]