MATHEMATICS
MIDDLE SCHOOL

Answer:

You times 2.25 x 6

So he paid .25 cents in sales tax

Answer: It would be $27.25 because you multiply $2.25 by 6 you should get $13.50 then add the $13.75 and you will get $27.25

HIGH SCHOOL

The half-life of iodine-124 is 4 days. A technician measures a 40-mCi sample of iodine-124. How many half-lives of iodine-124 occur in 16 days? How much iodine-124 is in the sample 16 days after the technician measures the original sample?

Answer:

The answer to your question is:

a) 4 half-life

b) 2.5 mCi

Step-by-step explanation:

Half-life of iodine 124 is 4 days

# of half- lives in 16 days = ?

Process

0 days ----------------- 0 half-life

4 days ------------------ 1 half life

8 days ------------------ 2 halves lives

12 days ----------------- 3 halves lives

16 days ----------------- 4 halves lives

b) 40 mCi ---------------- initially

20 mCi ---------------- 1 half life

10 mCi ---------------- 2 half life

5 mCi ---------------- 3 half life

2.5 mCi ---------------- 4 half life

Answer:

3 half-lives; 3.125 mCi

Step-by-step explanation:

A half-life of carbon-11 is 20min, so there are 60÷20=3half-lives in 1 hour.Let x=the number of half-livesin 1 hour, 3.Let y=the sample size after 1hour.Let a=the starting sample size,25 mCi.Let b=the decay factor orhalf-life, 0.5.y ====a•bx25•0.5325•0 . 1253 . 125 A half life of carbon 11 is 20 minutes, so there are 60 divided by 20 equals 3 half lives in 1 hour. Let x equal the number of half lives in 1 hour, 3. Let y equal the sample size after 1 hour. Let a equal the starting sample size, 25 millicuries. Let b equal the decay factor or half life, 0.5. Y equals a multiplied by b raised to the power of x. Equals 25 multiplied by 0.5 cubed. Equals 25 multiplied by 0.125. Equals 3.125.

COLLEGE

A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time is less than 7.6 hours.

Answer: 0.0026

Step-by-step explanation:

Given: Mean :

Standard Deviation :

Sample size :

Formula to calculate z-score :-

For X=7.6 hours.

Hence, the probability that their mean rebuild time is less than 7.6 hours = 0.0026

The probability that their mean rebuild time is less than 7.6 hours is 0.0026

Explanation:A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time is less than 7.6 hours.

The Chevrolet Cavalier is the line of small cars produced for the model years 1982 until 2005 by Chevrolet. Mechanics is the physics area concerned with the motions of macroscopic objects. The mean is the number average. To calculate we add up all the numbers then divide by how many numbers there are. In other words it is the sum divided by the count.

Therefore the value of Xbar < 7.6 hours. from the standard normal table is 0.0026

Hence, the probability that their mean rebuild time is less than 7.6 hours is 0.0026 = 0.26%.

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COLLEGE

jill brought home a hat from her trip. she had paid $25 for it. liu liked the hat and gave jill $35 for it. a few days later jill bought it back for $45. then jill sold it again this time to her cousin allie for $55. did jill make money or lose money

Jill made money.

-25 + 35 = 10

10 - 45 = -35

-35 + 55 = 20

Hope it helped! :)

HIGH SCHOOL

Which is the exponential form of log7 90 = y?

Answer: The required exponential form of the given equation is

Step-by-step explanation: We are given to write the exponential form of the following logarithmic equation :

We will be using the following property of logarithms :

Therefore, the given equation implies that

Thus, the required exponential form of the given equation is

That would be

90 = 7^y

90 = 7^y

COLLEGE

19. In scientific notation, 670,000,000 + 700,000,000 = ? A. 1.37 × 10-9

B. 1.37 x 107

C. 1.37 x 108

D. 1.37 10°

E. 137 x 1015

1.37x10^9 is the correct answer

MIDDLE SCHOOL

Will got 16 out of 20 correct. If he continues at the same rate, how many questions would he get correct out of 75?

Answer:

60

Step-by-step explanation:

16/20 times 75

MIDDLE SCHOOL

How many pieces 8 7/8 in long can be cut from a piece of 36 ft stock ? allow 3/16 in kerf

36÷ 8 7/8 = 4 4/71 or (Decimal: 4.056338)

HIGH SCHOOL

The denarius was a unit of currency in ancient Rome. Suppose it costs the Roman government 101010 denarii per day to support 444 legionaries and 444 archers. It only costs 555 denarii per day to support 222 legionaries and 222 archers. Use a system of linear equations in two variables. Can we solve for a unique cost for each soldier?

Let cost for each legionary be L

and that for each archer be A

We know that the system of linear equations that represent the information given in the question is :

- 444×L + 444×A = 101,010
- 222×L + 222×A = 555

We will notice that the above two equations represent the same line:

Divide the first equation by 222

⇒ 2×L + 2×A = 450

Now, divide the second equation by 11

⇒ 2×L + 2×A = 5

We can see that simplified versions of equations 1 and 2, lead to 2×L + 2×A being equal to different numbers

Hence, this system of equations is inconsistent. Hence, they have no solution, so we can't have a unique cost for each soldier.

Answer:

There are many solutions

Step-by-step explanation:

MIDDLE SCHOOL

Apply the distributive property to create an equivalent expression.

(6m -7) x 4

Hi there! the answer is...

24m - 28 is equivalent to (6m - 7) x 4

hope this helped! have a good one!

24m - 28 is equivalent to (6m - 7) x 4

hope this helped! have a good one!