All categories

3 years ago

Help me pls and pls explain

Mathematics

1 answer:

Luda [366]3 years ago

8 0

Answer:

5.1 mph

Step-by-step explanation:

she ran 3 2/5 miles in 2/3 hours.

that is the essential information to solve the problem. everything else is just there to give you "atmosphere" and Shao to confuse you.

the question is simply : what was her speed in mph ?

that means we need to bring the ratio of

3 2/5 miles / 2/3 hours

to 1 hour in the denominator (instead of 2/3 hours).

because we need that to express miles per (one) hour.

so, what do we need to multiply 2/3 with to get 1 (=3/3) ?

2/3 × x = 1

2x = 3

x = 3/2

so, to get 1 hour, we need to multiply the denominator by 3/2.

and to keep the original value of the ratio, we need to multiply also the numerator by the same 3/2.

speed = (3 2/5 miles × 3/2) / (2/3 hours × 3/2) =

= (17/5 miles × 3/2) / (1 hour) = 51/10 miles / 1 hour =

= 5.1 miles / 1 hour = 5.1 mph

You might be interested in

If a 12 ounce glass of ale contains 124 calories, how many calories are in 10 ounces?

Anestetic [448]

Answer

103.333333333

Explanation

Since 12oz of ale contains 124 calories, you have to divide 124 by 12 to find how many calories are in 1 oz of ale. then you multiply 10.33 by 10 to find how many calories are in a 10oz glass of ale.

5 0

3 years ago

Read 2 more answers

(1,10), (18.-10) slope

kobusy [5.1K]

Answer:

I think the slope is -20/17 hope this helps

8 0

3 years ago

Time spent using e-mail per session is normally distributed, with mu equals 11 minutes and sigma equals 3 minutes. Assume that

liq [111]

Answer:

a) 0.259

b) 0.297

c) 0.497

Step-by-step explanation:

To solve this problem, it is important to know the normal probability distribution and the central limit theorem.

Normal probability distribution

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central limit theorem

The Central Limit Theorem estabilishes that, for a random variable X, with mean $\mu$ and standard deviation $\sigma$ , a large sample size can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$

In this problem, we have that:

$\mu = 11, \sigma = 3$

a. If you select a random sample of 25 sessions, what is the probability that the sample mean is between 10.8 and 11.2 minutes?

Here we have that $n = 25, s = \frac{3}{\sqrt{25}} = 0.6$

This probability is the pvalue of Z when X = 11.2 subtracted by the pvalue of Z when X = 10.8.

X = 11.2

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{11.2 - 11}{0.6}$

$Z = 0.33$

$Z = 0.33$ has a pvalue of 0.6293.

X = 10.8

$Z = \frac{X - \mu}{s}$

$Z = \frac{10.8 - 11}{0.6}$

$Z = -0.33$

$Z = -0.33$ has a pvalue of 0.3707.

0.6293 - 0.3707 = 0.2586

0.259 probability, rounded to three decimal places.

b. If you select a random sample of 25 sessions, what is the probability that the sample mean is between 10.5 and 11 minutes?

Subtraction of the pvalue of Z when X = 11 subtracted by the pvalue of Z when X = 10.5. So

X = 11

$Z = \frac{X - \mu}{s}$

$Z = \frac{11 - 11}{0.6}$

$Z = 0$

$Z = 0$ has a pvalue of 0.5.

X = 10.5

$Z = \frac{X - \mu}{s}$

$Z = \frac{10.5 - 11}{0.6}$

$Z = -0.83$

$Z = -0.83$ has a pvalue of 0.2033.

0.5 - 0.2033 = 0.2967

0.297, rounded to three decimal places.

c. If you select a random sample of 100 sessions, what is the probability that the sample mean is between 10.8 and 11.2 minutes?

Here we have that $n = 100, s = \frac{3}{\sqrt{100}} = 0.3$

This probability is the pvalue of Z when X = 11.2 subtracted by the pvalue of Z when X = 10.8.

X = 11.2

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{11.2 - 11}{0.3}$

$Z = 0.67$

$Z = 0.67$ has a pvalue of 0.7486.

X = 10.8

$Z = \frac{X - \mu}{s}$

$Z = \frac{10.8 - 11}{0.3}$

$Z = -0.67$

$Z = -0.67$ has a pvalue of 0.2514.

0.7486 - 0.2514 = 0.4972

0.497, rounded to three decimal places.

5 0

3 years ago

Solve the inequality below. Use the drop down menus' to describe the solution and its graph.

defon

Answer:

x>-4

Step-by-step explanation:

Easy, -7x + 13 > 41 from here you subtract 13 from each side giving you -7x >28 after this you divide by -7.

3 0

2 years ago

A 40% sugar solution is added to an 85% sugar solution to create 1800 mL of a 60% solution. How much of each solution is used? (

denis-greek [22]

Answer:

Number of ml of 40% sugar = x = 1000mL

Number of ml of 85% sugar used = y = 800mL

Step-by-step explanation:

Let the

Number of ml of 40% sugar = x

Number of ml of 85% sugar used = y

From the above question, our system of equations is given as:

x + y = 1800mL ....... Equation 1

x = 1800 - y

40% × x + 85% × y = 60% × 1800mL

0.4x + 0.85y = 1080.... Equation 2

We substitute 1800 - y for x in Equation 2

0.4(1800 - y) + 0.85y = 1080

720 - 0.4y + 0.85y = 1080

- 0.4y + 0.85y = 1080 - 720

0.45y = 360

y = 360/0.45

y = 800mL

Solving for x

x = 1800 - y

x = 1800 - 800

x = 1000mL

Therefore,

Number of ml of 40% sugar = x = 1000mL

Number of ml of 85% sugar used = y = 800mL

4 0

3 years ago