Solve this system of equations using any method. 2x – y = 5 4x + y =7

1 answer:

8 0

Substitute on equation 2, y = -4x + 7. so equation 1 becomes 2x - (-4x + 7) = 6x - 7 = 5. 6x = 12, so x = 2. from above, y = -4x+7 = -4(2) + 7 = -1

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To begin a bacteria study, a petri dish had 2800 bacteria cells. Each hour since, the number of cells has increased by 7.2%. Let

Rudiy27

The function that models exponential growth is:

P(t) = P0*(1 + r)^t, where

P0 = P(0) is the initial value of P

r is the growth rate as a decimal

In our case we have:

P(0) = 2800

r = 0.035 or 3.5%

P(t) = 2800*(1 + 0.035)^t

P(t) = 2800*(1.035)^t

The same exponential function written using y and t is:

y = 2800*1.035^t.

Explanation: https://softmath.com/algebra-word-problems/to-begin-a-bacteria-study-a-petri-dish-had-2800-bacteria

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An English professor assigns letter grades on a test according to the following scheme. A: Top 15% of scores B: Scores below the

lisabon 2012 [21]

Answer:

59 to 66

Step-by-step explanation:

Mean test scores = u = 74.2

Standard Deviation = $\sigma$ = 9.6

According to the given data, following is the range of grades:

Grade A: 85% to 100%

Grade B: 55% to 85%

Grade C: 19% to 55%

Grade D: 6% to 19%

Grade F: 0% to 6%

So, the grade D will be given to the students from 6% to 19% scores. We can convert these percentages to numerical limits using the z scores. First we need to to identify the corresponding z scores of these limits.

6% to 19% in decimal form would be 0.06 to 0.19. Corresponding z score for 0.06 is -1.56 and that for 0.19 is -0.88 (From the z table)

The formula for z score is:

$z=\frac{x-u}{\sigma}$