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3 years ago

How many 2 digit whole numbers are increased by 18 when they're digits are reversed

Mathematics

1 answer:

Anika [276]3 years ago

8 0

This can be calculated easily.

As any two digit number can be written in the following form:

N= 10x +y

If we reverse the number now, it would become:

N' = 10y + x

So if we subtract one from the other, we should obtain 18 ( as mentioned in the question ).

N-N'= 18

=> x-y = 2

Thus, any number whose digits differ by two would be an aswer to the question.

The only numbers which satisfy this are : 13,24,35,46,57,68,79

But this would not be true for any 3 or more digit number.

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Osama starts with a population of 1,000 amoebas that increases 30% in size every hour for a number of hours, h. The expression 1

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Answer: The correct option is A, itis the product of the initial population and the growth factor after h hours.

Explanation:

From the given information,

Initial population = 1000

Increasing rate or growth rate = 30% every hour.

No of population increase in every hour is,

$1000\times \frac{30}{100} =1000\times 0.3$

Total population after h hours is,

$1000(1+0.3)^h$

It is in the form of,

$P(t)=P_0(t)(1+r)^t$

Where $P_0(t)$ is the initial population, r is increasing rate, t is time and [tex(1+r)^t[/tex] is the growth factor after time t.

In the above equation 1000 is the initial population and $(1+0.3)^h$ is the growth factor after h hours. So the equation is product of of the initial population and the growth factor after h hours.

Therefore, the correct option is A, itis the product of the initial population and the growth factor after h hours.

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3 years ago

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An automobile manufacturer has given its van a 59.5 miles/gallon (MPG) rating. An independent testing firm has been contracted t

LekaFEV [45]

Answer:

The pvalue of the test is 0.0124 < 0.1, which means that there is sufficient evidence at the 0.1 level to support the testing firm's claim.

Step-by-step explanation:

An automobile manufacturer has given its van a 59.5 miles/gallon (MPG) rating. An independent testing firm has been contracted to test the actual MPG for this van since it is believed that the van has an incorrect manufacturer's MPG rating:

At the null hypothesis, we test if the mean is the same, that is:

$H_0: \mu = 59.5$

At the alternate hypothesis, we test that it is different, that is:

$H_a: \mu \neq 59.5$

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.

59.5 is tested at the null hypothesis:

This means that $\mu = 59.5$

After testing 250 vans, they found a mean MPG of 59.2. Assume the population standard deviation is known to be 1.9.

This means that $n = 250, X = 59.2, \sigma = 1.9$

Value of the test statistic:

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

$z = \frac{59.2 - 59.5}{\frac{1.9}{\sqrt{250}}}$

$z = -2.5$

Pvalue of the test and decision:

The pvalue of the test is the probability of finding a mean that differs from 59.5 by at least 0.3, which is P(|Z|>-2.5), which is 2 multiplied by the pvalue of Z = -2.5.

Looking at the z-table, Z = -2.5 has a pvalue of 0.0062

2*0.0062 = 0.0124

The pvalue of the test is 0.0124 < 0.1, which means that there is sufficient evidence at the 0.1 level to support the testing firm's claim.

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3 years ago

What is 7 7/8 dvided by 3 1/8 mixed numbers

zhannawk [14.2K]

Answer:

2.52

Step-by-step explanation:

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Ursula picks carrots and radishes from her garden. She picks

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2 1/2 more pounds of carrots.

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Mr. Vogel is riding the stationary bike at the gym. He completes 41 1/2 wheel rotations even 1/3 minute. what Mr Vogel's unit ra

Eva8 [605]

1/3times3=3/3 3/3 is the same as a whole so do 41 and 1/2 times 3 this gets you an answer of 124.5 meaning the unit 124.5x he makes 124.5 rotations per minute

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3 years ago