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3 years ago

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Last week, Chen bought 812 gallons of gas at $2.30 per gallon. This week, he bought 4310 gallons of gas at $2.70 per gal

lon.
What was his total cost?

1 answer:

allsm [11]3 years ago

5 0

Answer:

13054.6

Step-by-step explanation:

multiply 812 by 2.30 then multiply 4310 by 2.70 then add both answers together.

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A manufacturer of golf equipment wishes to estimate the number of left-handed golfers. A previous study indicates that the propo

never [62]

Answer:

A sample of 997 is needed.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the z-score that has a p-value of $1 - \frac{\alpha}{2}$ .

The margin of error is of:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

A previous study indicates that the proportion of left-handed golfers is 8%.

This means that $\pi = 0.08$

98% confidence level

So $\alpha = 0.02$ , z is the value of Z that has a p-value of $1 - \frac{0.02}{2} = 0.99$ , so $Z = 2.327$ .

How large a sample is needed in order to be 98% confident that the sample proportion will not differ from the true proportion by more than 2%?

This is n for which M = 0.02. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.02 = 2.327\sqrt{\frac{0.08*0.92}{n}}$

$0.02\sqrt{n} = 2.327\sqrt{0.08*0.92}$

$\sqrt{n} = \frac{2.327\sqrt{0.08*0.92}}{0.02}$

$(\sqrt{n})^2 = (\frac{2.327\sqrt{0.08*0.92}}{0.02})^2$

$n = 996.3$

Rounding up:

A sample of 997 is needed.

3 0

3 years ago

The volume V of a gas varies inversely as the pressure P and directly as the temperature A certain gas has a volume of 10 liters

Ad libitum [116K]

Answer:

Joint variation states that:

If z is directly proportional to x and inversely proportional to y,

i.e, $z \propto x$ , $z \propto \frac{1}{y}$

then the equation is in the form: $z = k\frac{x}{y}$ where k is the constant of variation.

From the given information: The volume V of a gas varies inversely as the pressure P and directly as the temperature

i.,e $V \propto T$ , $V \propto \frac{1}{P}$

by definition of joint variation:

$V = k\frac{T}{P}$ .....[1] where k is the constant of variation.

It is also given that a certain gas has a volume of 10 liters(L) , a temperature of 300 kelvins(K), and a pressure of 1.5 atmosphere(atm).

Substitute these given values in [1] to solve for k;

$10 = k\frac{300}{1.5}$

Simplify:

$10 = 200k$

Divide by 200 both sides we have;

$k = \frac{10}{200} =\frac{1}{20}$

Now, if a gas has a temperature of 400 kelvins and a pressure of 5 atm.

To find the volume (V);

Now substitute the given data and value of k in [1] we have;

$V = \frac{1}{20} \cdot \frac{400}{5} = \frac{20}{5} = 4$

Therefore, the Volume of a gas is, 4 liters

5 0

3 years ago

Find the interest earned.

MakcuM [25]

September
30-10=20 days
October 31
November 10
Time=20+31+10=61 days
A=42,000×(1+0.035÷365)^(61)
A=42,246.38
Interest earned
I=42,246.38−42,000
I=246.38

5 0

3 years ago

6-2x??? NEED AN ANSWER ASAP!!!

JulijaS [17]

Answer:

2(3-x)

Step-by-step explanation:

3 0

3 years ago

A box of 3 picture hangers sells for $2.22. What is the unit rate

Anestetic [448]

Answer:

0.74 cents each unit piece

Step-by-step explanation:

2.22 ÷ 3 = 0.74

7 0

3 years ago