Please help me on number 2

A manufacturer must test that his bolts are 4.00 cm long when they come off the assembly line. He must recalibrate his machines

storchak [24]

Answer:

The null hypothesis is $H_o: \mu = 4$ .

The alternate hypothesis is $H_a: \mu \neq 4$

The pvalue of the test is 0.0182 < 0.05, which means that there is sufficient evidence to show that the manufacturer needs to recalibrate the machines.

Step-by-step explanation:

A manufacturer must test that his bolts are 4.00 cm long when they come off the assembly line.

This means that the null hypothesis is that they are 4.00 cm long, that is:

$H_o: \mu = 4$

At the alternate hypothesis we test if it is different. So

$H_a: \mu \neq 4$

The test statistic is:

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

In which X is the sample mean, $\mu$ is the value tested at the null hypothesis, $\sigma$ is the standard deviation and n is the size of the sample.

4 is tested at the null hypothesis:

This means that $\mu = 4$

After sampling 196 randomly selected bolts off the assembly line, he calculates the sample mean to be 4.14 cm.

This means that $n = 196, X = 4.14$

He knows that the population standard deviation is 0.83 cm.

This means that $\sigma = 0.83$

Value of the test statistic:

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

$z = \frac{4.14 - 4}{\frac{0.83}{\sqrt{196}}}$

$z = 2.36$

Pvalue of the test and decision:

The pvalue of the test is the probability that the sample mean is different by at least 4.14 - 4 = 0.14 from the target value, which is P(|z| > 2.36), which is 2 multiplied by the pvalue of z = -2.36.

Looking at the z-table, z = -2.36 has a pvalue of 0.0091

2*0.0091 = 0.0182

The pvalue of the test is 0.0182 < 0.05, which means that there is sufficient evidence to show that the manufacturer needs to recalibrate the machines.

5 0

3 years ago

I need help in factoring this trinomial. 10y^3-17y + 3y

Viefleur [7K]

Y(2y-3)(5y-1) check using foil

5 0

3 years ago

A square pyramid has a base area of 25 square inches, and a volume of 150 cubic inches. What is the height of the pyramid in inc

KonstantinChe [14]

Answer:

Step-by-step explanation:

3 0

4 years ago

On a baseball team, the ages of each of the players are as follows: 21; 21; 22; 23; 24; 24; 25; 25; 28; 29; 29; 31; 32; 33; 33;

Paul [167]

Answer:

Mean = 30.68

Standard deviation = 6.095

Two standard deviations above the mean = 42.87

Step-by-step explanation:

Given the following data :

21; 21; 22; 23; 24; 24; 25; 25; 28; 29; 29; 31; 32; 33; 33; 34; 35; 36; 36; 36; 36; 38; 38; 38; 40

Mean = Σ(x) / n

n = 25

Σ (X) = 767

Mean (m) = 767 / 25

Mean (m) = 30.68

Standard deviation : sqrt[Σ(x - m) / n]

Using a calculator :

Standard deviation = 6.095 ( 2 decimal places)

2 standard deviations above the mean :

Mean + 2(standard deviation)

Mean + 2(6.095)

30.68 + 12.19

= 42.87

6 0

4 years ago

1. Suzie had d DVDs. Her mother bought her 39 more DVDs.

Fantom [35]

Answer:

1. The expression that represents the total number of DVDs Suzie has is d + 39

2. The expression for the amount Dave pays for t hours of practice in a month is 10 + 2 × t

3. The expression for the total cost for n people invited for the party is $50 + $5 × n

4. The expression for the perimeter of a square with side length, x is 4 × x

5. The expression for the total cost of pizza with n extra toppings is $8 + $2 × n

6. The expression for the total cost in phone charges after t months is $25 + t × $15

7. The expression for the total number of hockey sticks for n players is 4 × n

8. The relation that represent the term for each number pattern is given as follows;

Value = nth term of number

9. The relation for the perimeter of an equilateral triangle with side length k is given as follows;

Perimeter of an equilateral = 3 × Side length

∴ Perimeter of the given equilateral triangle = 3 × k

When k = 15, we have;

Perimeter of the equilateral triangle = 3 × 15 cm = 45 cm

10. a) The relation for the total cost of j jersey is $50 + $15 × j

b) The relation for the total cost of j jersey by the other company is $80 + $12 × j

c) The charges for 12 jerseys by the first company is $50 + $15 × 12 = $230

The charges for 12 jerseys by the first company is $80 + $12 × 12 = $224

Therefore, the second company will charge less if 12 jerseys are ordered

11. The real life situation that could be represented by each relation are;

a. n + 7

For every mass in grams of goods bought, n, we get a 7 gram mass of packaging

b. 4s + 5

The distance from a point covered by jogging at 4 m/s after s seconds while starting at 5 meters away from the point in the direction of jogging

12. a) The relation for the total number of music stand is n/2

b) The relation for the total number of chairs is n + 4

c) The relation for the total number of sheets of music is 7 × n

Step-by-step explanation:

8 0

3 years ago