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3 years ago

Get brainly if right!!

Mathematics

2 answers:

slava [35]3 years ago

5 0

Answer:

$6\text{ mph}$

Step-by-step explanation:

To find the the distance between A and B, use $d=rt$ , where $d$ is distance, $r$ is rate/speed, and $t$ is time.

The raft travels from A to B in 6 hours at a rate of 3 mph. Thus, the distance from A to B must be:

$d=3\cdot 6=18$ miles.

Since the motorboat travels the same distance in 2 hours, its rate/speed must be:

$18=2r,\\r=\frac{18}{2}=9\text{ mph}$

Because the raft is drifting, the speed of the current must be $3\text{ mph}$ in the direction of the raft (from A to B). Thus, let the motorboat's speed be $m$ :

$m+3=9,\\n=\boxed{6\text{ mph}}$

juin [17]3 years ago

4 0

Answer:

Time taken by the un powered raft to cover this distance is T = 192.12 hr

Step-by-step explanation:

Let speed of boat = u

Speed of current = v

Let distance between A & B = 100 km

Time taken in downstream = 32 hours

u + v = 3.125 ------ (1)

Time taken in upstream = 48 hours

u - v = 2.084 ------- (2)

By solving equation (1) & (2)

u = 2.6045

v = 0.5205

Now the time taken by the un powered raft to cover this distance

Because un powered raft travel with the speed of the current.

T = 192.12 hr

Therefore the time taken by the un powered raft to cover this distance is

T = 192.12 hr

You might be interested in

Of the total population of American households, including older Americans and perhaps some not so old, 17.3% receive retirement

Alex Ar [27]

Answer:

47.54% probability that more than 20 households but fewer than 35 households receive a retirement income

Step-by-step explanation:

We use the binomial aproxiation to the normal to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed samples can be 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.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .

In this problem, we have that:

$p = 0.173, n = 120$ . So

$\mu = E(X) = np = 120*0.173 = 20.76$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{120*0.173*0.827} = 4.14$

In a random sample of 120 households, what is the probability that more than 20 households but fewer than 35 households receive a retirement income?

We are working with discrete values, so this is the pvalue of Z when X = 35-1 = 34 subtracted by the pvalue of Z when X = 20 + 1 = 21.

X = 34

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

$Z = \frac{34 - 20.76}{4.14}$

$Z = 3.2$

$Z = 3.2$ has a pvalue of 0.9993

X = 21

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

$Z = \frac{21 - 20.76}{4.14}$

$Z = 0.06$

$Z = 0.06$ has a pvalue of 0.5239

0.9993 - 0.5239 = 0.4754

47.54% probability that more than 20 households but fewer than 35 households receive a retirement income

6 0

4 years ago

the length and width of a rectangle are whole numbers of centimeters. neither is divide by 6.the area of the rectangle is 36 squ

liraira [26]

Note that

36=1·36;
36=2·18;
36=3·12;
36=4·9;
36=6·6.

If neither (length and width) is divide by 6, then cases 1, 2, 3 and 5 are extra, because

36:6=6 (is divide by 6);
18:6=3 (is divide by 6);
12:6=2 (is divide by 6);
6:6=1 (is divide by 6).

The only possible dimensions are: width - 4 cm and length - 9 cm.

Then the perimeter is

$P=4+9+4+9=26$ cm.

Answer: 26 cm.

3 0

3 years ago

How many hundredths in 45.972

timama [110]

It's the 7 because it"s in the hundredths spot. So it makes it 7 hundredths.

6 0

3 years ago

Please help me on this one

devlian [24]

Answer:

option a

step-by-step explanation:

To rationalize the expresion we need to multiply and divide the expression by the conjugate of the denominator as follows

sqrt(9) / (sqrt(3) + sqrt(x)) = sqrt(9) ((sqrt(3) - sqrt(x)) / ((sqrt(3) + sqrt(x))(sqrt(3) - sqrt(x)))

3((sqrt(3) - sqrt(x)) / (3 - x)

So the result es option a:

(3sqrt(3) - 3sqrt(x)) / (3 - x)

4 0

3 years ago

I forgot to do slopes

Minchanka [31]

To find the slope of the line, use the rise over run formula:

$\frac{y_{2} - y_{1}}{x_{2} - x_{1}}$

Take any two points from the line and plug them into the formula.

(0,0) and (10, 5)

$\frac{5 - 0}{10 - 0} = \frac{5}{10} = 0.5$

The slope of the line is 0.5.

Using the form y = mx, the following equation will be your answer:

$y = 0.5x$

7 0

3 years ago