What are the zeros of the function f(x)= x^2-144

A company with a large fleet of cars wants to study the gasoline usage. They check the gasoline usage for 50 company trips chose

Nookie1986 [14]

Answer:

The 95% confidence interval is given by (25.71536 ;28.32464)

And if we need to round we can use the following excel code:

round(lower,2)

[1] 25.72

round(upper,2)

[1] 28.32

And the interval would be (25.72; 28.32)

Step-by-step explanation:

Notation and definitions

n=50 represent the sample size

$\bar X= 27.2$ represent the sample mean

$s=5.83$ represent the sample standard deviation

m represent the margin of error

Confidence =88% or 0.88

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

Calculate the critical value tc

In order to find the critical value is important to mention that we don't know about the population standard deviation, so on this case we need to use the t distribution. Since our interval is at 88% of confidence, our significance level would be given by $\alpha=1-0.88=0.12$ and $\alpha/2 =0.06$ . The degrees of freedom are given by:

$df=n-1=50-1=49$

We can find the critical values in R using the following formulas:

qt(0.06,49)

[1] -1.582366

qt(1-0.06,49)

[1] 1.582366

The critical value $tc=\pm 1.582366$

Calculate the margin of error (m)

The margin of error for the sample mean is given by this formula:

$m=t_c \frac{s}{\sqrt{n}}$

$m=1.582366 \frac{5.83}{\sqrt{50}}=14.613$

With R we can do this:

m=1.582366*(5.83/sqrt(50))

m

[1] 1.304639

Calculate the confidence interval

The interval for the mean is given by this formula:

$\bar X \pm t_{c} \frac{s}{\sqrt{n}}$

And calculating the limits we got:

$27.02 - 1.582366 \frac{5.83}{\sqrt{50}}=25.715$

$27.02 + 1.582366 \frac{5.83}{\sqrt{50}}=28.325$

Using R the code is:

lower=27.02-m;lower

[1] 25.71536

upper=27.02+m;upper

[1] 28.32464

The 95% confidence interval is given by (25.71536 ;28.32464)

And if we need to round we can use the following excel code:

round(lower,2)

[1] 25.72

round(upper,2)

[1] 28.32

And the interval would be (25.72; 28.32)

6 0

3 years ago

C=-3. a=2 b=4 (2) 2(3c+7)

Paha777 [63]

I think the answer is -18 + 14

4 0

2 years ago

Haley measured the distances between her house and two of her friends' houses. ellen's house is 1.41 miles away from haley's, an

Arada [10]

Answer: Ellen's house is farther away by 898 feet.

Step-by-step explanation:

Given: The distance between Haley's house and Ellen's house = 1.41 miles

We know that 1 mile = 5,280 feet

Then, $1.41\text{ miles}=1.41\times5,280\text{ feet}=7,444.8\text{ feet}$

The distance between Haley's house and Dirk's house = 6,547 feet

Clearly, 6,547<7,444.8

And $7444.8-6547= 897.8\approx898$

Therefore, Ellen's house is farther away by 898 feet.

3 0

3 years ago

Read 2 more answers

Is 2 1/5 × 1 1/4 greater, equal, or less than 1 1/4

Zielflug [23.3K]

Answer:

2 1/5 x 1 1/4 is greater than 1 1/4

3 0

2 years ago

28/29 and 30 plz short explanation thanks

iren2701 [21]

Integers are numbers like ...-3, -2, -1, 0, 1, 2, 3... and so on. So, according to this definition, let's solve this problem:

28. We know that the product of three integers is -3. So, the statement states that we have three factor, so:

a.b.c = -3

The possible values of the factors are:

Factors are: 3, 1 and -1 in which case:

(3)(1)(-1) = -3

Factors are: -3, 1 and 1 in which case:

(-3)(1)(1) = -3

29. In this problem we know two nonzero integers, that is, they cannot be equal to zero. Thus, they must have different sign, that is, one of them must be positive and the other negative. For instance:

-9 and 2

(-9)(2) = -18, So -18 is less than -9 and 2

Another example:

1 and -8

(1)(-8) = -8, So -8 is equal to -8 and -8 is less than 1.

30. The sign of the product of two integers with the same sign is positive, that is:

(+)(+) = (+) and

(-)(-) = (+)

So, the sign of the product of three integers with the same sign are two options:

Option 1. The three integers are positive in which case:

(+)(+)(+) = (+), So the sign of the product is positive

Option 2. The three integers are negative in which case:

(-)(-)(-) = (-), So the sign of the product is negative.

This option two gives us that result because:

(-)(-) = (+) and (+)(-) = (-)

8 0

2 years ago