A man is five times as old as his son. Four years ago, he was nine times as old. Find their present ages.

Answers

Answer 1

Answer: Let us assume the age of the son now = x
Then
The age of the man now = 5x
Now we have to calculate the age of the son and father 9 years ago
Age of the son 4 years ago = x - 4
Age of the man 4 years ago = 5x - 4
Then
5x - 4 = 9(x - 4)
5x - 4 = 9x - 36
5x - 9x = -36 + 4
- 4x = - 32
MUltiplying both sides of the equation by -1 we get
4x = 32
x = 32/4
= 8
So the present age of the son is 8 years
Present age of the man = 5x
= 5 * 8
= 40 years
So the present age of the man is 40 years and the present age of the son is 8 years.

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The original price of an electric scooter was $187.50. The scooter was on sale for $165. What was the discount rate?

Answers

so the origiinal price is 187.50 and the sale price was 165, so the discount is 187.50 - 165 = 22.5.

if we take 187.50 to be the 100%, what is 22.5 off of it in percentage?

$\bf \begin{array}{ccll} amount&\%\n \cline{1-2} 187.5&100\n 22.5&x \end{array}\implies \cfrac{187.5}{22.5}=\cfrac{100}{x}\implies 187.5x=2250 \n\n\n x=\cfrac{2250}{187.5}\implies x=12$

Answer: I got 12% after trial an error from 15% down to 12% when i got 165$

Lucy correctly answered 70% of the questions on her science homework. She counted 14 correct answers. How many questions are there on her homework?

Answers

Answer:

9.8

Step-by-step explanation:

5y(2y-3)=(2y-3) can someone help me and explain step by step on how to do it

Answers

First you must add the same numbers together, for instance, you wouldn't add 4y with 4 you have to add it with another number that is just like it, for instance 4y and 9y they are the same, so you can add them. So let's get to the problem now: 5y(2y-3)=(2y-3) 5y*2y=10y (10y-3)=(2y-3) You can do nothing to the other side because there are no numbers, that are the same.

Solve 1/2n + 3 < 5 ??

Answers

Answer:

n<4

Step-by-step explanation:

Answer:

$n < 4$

Step-by-step explanation:

$(1)/(2) n + 3 < 5 \n subtract \: 3 \: from \: both \: sides \n \n (1)/(2) n < 2 \n divide \: both \: sides \: by \: (1)/(2) \n \n n < 4$

the environmental protection agency has determined that safe drinking water should contain no more than 1.3 milligrams per liter (mg/l) of copper, on average. to test water from a new source, you collect water in small bottles at each of 30 randomly selected locations. the mean copper content of your bottles is 1.36 mg/l and the standard deviation is 0.18 mg/l. you perform a test of

Answers

The EPA has set the safe drinking water limit for copper at 1.3 milligrams per liter (mg/L). In your sample, the mean copper content is 1.36 mg/L with a standard deviation of 0.18 mg/L from 30 randomly selected locations.

To determine if the new water source meets the EPA's standard, you should perform a hypothesis test using the provided sample data. The null hypothesis (H0) would be that the mean copper content is less than or equal to 1.3 mg/L, while the alternative hypothesis (H1) is that the mean copper content is greater than 1.3 mg/L.

With the given sample size, mean, and standard deviation, you can calculate the test statistic and compare it to a critical value to determine whether to accept or reject the null hypothesis. If the test statistic is greater than the critical value, you would reject the null hypothesis and conclude that the mean copper content of the new water source exceeds the EPA's safe limit.

It's important to remember that statistical tests can only provide evidence for or against a hypothesis, but cannot definitively prove that the new water source is safe or unsafe. Additional testing and monitoring would be necessary to make a well-informed decision about the safety of the water source.

To learn more about null hypothesis : brainly.com/question/28920252

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You have $28.49. You spend $14.95 at a bowling alley. You win $35.00 for setting the record score for your age group. How much money do you have now?

Answers

Answer:

48.54‬

Step-by-step explanation:

You start of with 28.49, you spend (Subtract) 14.95, which gives us 13.54

In the bowling alley you win 35 dollars more, so you add, ( 13.54 + 35.00 = 48.54‬)

the answer is $48.54

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