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3 years ago

Brian scored 120 on his test the first time he took the test. The second time he took the test,

Mathematics

2 answers:

Brums [2.3K]3 years ago

6 0

Answer:

b. 25%

Step-by-step explanation:

(new - old)/ old * 100%

150 - 120 = 30 ... 30/120 = .25 * 100% = 25%

Kruka [31]3 years ago

5 0

Answer:

25% increase

Step-by-step explanation:

Take the new amount and subtract the original amount

150-120

Divide this by the original amount

30/120

1/4

.25

Multiply by 100%

25%

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Solve -7x = 21 X = please help ASAP

Tomtit [17]

Answer: x = -3

Step-by-step explanation:

i simply divided by -7, in order to get x by itself.

-7/-7x = 21/-7

that cancels out the -7 on the left side, and leaves us with -3 on the right side!

x = -3

6 0

3 years ago

Read 2 more answers

Problem page a long distance runner starts at the beginning of a trail and runs at a rate of 6 miles per hour. one hour later, a

alukav5142 [94]

The thing you have to figure out about this is the distance for each person and the time it takes for the biker to meet the runner. The rates we are told. The formula is distance = rate times time. Let's do that for the runner first. His rate is 6 so the formula so far is d = 6t. Now let's work on the time. If the biker left an hour later than the runner, then the runner has been running an hour more than the biker. Therefore, the runner's time is t + 1. Hold off on the distance part til we do for the biker what we just did for the runner. The biker's rate is 14, and we already decided that his time is t. His equation is d = 14t. Now at the exact moment the biker meets the runner their distances are the same. So if the equation for the runner is d = 6t + 6 and the equation for the biker is d = 14t and their distances are the same, by the transitive property, their rates and times are the same as well, meaning we set them equal to each other and solve for t. 6t + 6 = 14t. 6 = 8t and t = 3/4. This means that it took 45 minutes for the biker to meet the runner.

5 0

3 years ago

I need help with 23 please!!!

Sever21 [200]

Answer:

28 questions

Step-by-step explanation:

In the first 10 mins she answered 2/5 of 40 which is 16. The remaining amount is 24 questions and half of that is 12. So she answered 12 questions in 15 mins. Finally you add them to get 28 questions in 25 minutes.

3 0

3 years ago

Suppose that the amount of time T a customer spends in a bank is exponentially distributed with an average of 10 minutes. What i

Bad White [126]

Answer:

The probability that a customer will spend more than 15 minutes total in the bank, given that the customer has already waited over 10 minutes is 0.6065.

Step-by-step explanation:

The random variable T is defined as the amount of time a customer spends in a bank.

The random variable T is exponentially distributed.

The probability density function of a an exponential random variable is:

$f(x)=\lambda e^{-\lambda x};\ x>0$

The average time a customer spends in a bank is β = 10 minutes.

Then the parameter of the distribution is:

$\lambda=\frac{1}{\beta}=\frac{1}{10}=0.10$

An exponential distribution has a memory-less property, i.e the future probabilities are not affected by any past data.

That is, P (X > s + x | X > s) = P (X > x)

So the probability that a customer will spend more than 15 minutes total in the bank, given that the customer has already waited over 10 minutes is:

P (X > 15 | X > 10) = P (X > 5)

$\int\limits^{\infty}_{5} {f(x)} \, dx =\int\limits^{\infty}_{5} {\lambda e^{-\lambda x}} \, dx\\=\int\limits^{\infty}_{5} {0.10 e^{-0.10 x}} \, dx\\=0.10\int\limits^{\infty}_{5} {e^{-0.10 x}} \, dx\\=0.10|\frac{e^{-0.10 x}}{-0.10}|^{\infty}_{5}\\=[-e^{-0.10 \times \infty}+e^{-0.10 \times 5}]\\=0.6065$

Thus, the probability that a customer will spend more than 15 minutes total in the bank, given that the customer has already waited over 10 minutes is 0.6065.

8 0

3 years ago

What values of x and y satisfy the system of equations {10x+3y=−5−5x−4y=10? (0,−53) (25,−3) (−2,0) (12,−103)

Kitty [74]

Answer:

The solution of the equation

( 0.4 ,-3)

Step-by-step explanation:

Explanation:-

Step(i):-

Given system of equations

10 x+3 y = −5 ...(i)

- 5 x - 4 y = 10 ...(ii)

Multiply (i) with '5'

10 × 5 x + 3×5 y = - 25

50 x + 15 y = 25 ...(iii)

Multiply (ii) with '10'

-5 × 10 x - 4×1 0 y = 100

- 50 x - 40 y =100 ...(iv)

Step(ii):-

Solving (iii) and (iv)

50 x + 15 y =- 25

- 50 x - 40 y =100

- 25 y = 75

Dividing ' - 25' on both sides, we get

y = -3

substitute y = -3 in equation (i) , we get

10 x+3 y = −5

10 x - 9 = - 5

10 x = -5 + 9

$x = \frac{4}{10}$

x = 0.4

Final answer:-

The solution of the equation ( 0.4 ,-3)

7 0

3 years ago