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2 years ago

15

Mr johnson's students want to know his age. He tells them that this year his age is a multiple of 9, and next year it will be a

multiple of 4. What is his age?

1 answer:

vladimir1956 [14]2 years ago

8 0

Answer:

He is 27 years old.

Step-by-step explanation:

27 is a multiple of 9 (9 x 3)

28 comes after, and is a multiple of 4 (4 x 7)

Hope this answer helps you!! :)

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A book is on sale for $6 off of the regular $24 price. What percent is the discount?

Vika [28.1K]

6/24* 100= 25%. You multiply top ( 6 and 100) and divide to bottom (600 and 24) to get 25%.

8 0

3 years ago

Read 2 more answers

Reggie, Alvin, and Jose are member of a relay running team. Reggie finished his leg of the race 2.45 seconds faster than Alvin a

lorasvet [3.4K]

From the given, we expressed the time that each of the team members ran in mathematical expression.

Reggie = 57.12 seconds
Alvin = 57.12 + 2.45 seconds = 59.57 seconds
Jose = 57.12 - 3.81 seconds = 53.31 seconds
We then sum up all the time we calculate to determine the total time for the team. The answer is therefore 170 seconds.

8 0

2 years ago

The selling price of an item is $600. After 6 months of not selling, it is marked down by 30% . After another 6 months of not se

Bingel [31]

The sale price after both markdowns will be $336

<em><u>Explanation</u></em>

The selling price of an item is $600. After 6 months of not selling, it is marked down by 30%

So, the marked down amount after 6 months $=\$ 600*0.30= \$180$

and the selling price after first 6 months will be: $\$600-\$180=\$420$

After another 6 months of not selling , it is further marked down by 20%. So, the marked down amount now $= \$420*0.20=\$84$

Thus, the final selling price after all markdowns $=\$420-\$84=\$336$

4 0

3 years ago

The Information Technology Department at a large university wishes to estimate the proportion of students living in the dormitor

nadya68 [22]

Answer:

$n=\frac{0.5(1-0.5)}{(\frac{0.05}{1.96})^2}=384.16$

And rounded up we have that n=385

Step-by-step explanation:

Previous concepts

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".

Solution to the problem

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ . And the critical value would be given by:

$z_{\alpha/2}=-2.58, z_{1-\alpha/2}=2.58$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.05$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

We can use as an estimator for p $\hat p =0.5$ . And replacing into equation (b) the values from part a we got:

$n=\frac{0.5(1-0.5)}{(\frac{0.05}{1.96})^2}=384.16$

And rounded up we have that n=385

3 0

3 years ago

The cost of a fridge has increased by 15% to £828. Work out the original price

lilavasa [31]

The original value was <span>£720.
720 x .15 (15%) = 108
720 + 108 = 828 </span>

8 0

3 years ago