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3 years ago

75% of what number is 45? A:15 B:30 C:45 D:60

Mathematics

1 answer:

jarptica [38.1K]3 years ago

5 0

Answer:

D. 60= 100 % therefore, 45 would equal 75 %.The answers D. Hope this helps!

Step-by-step explanation:

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Sean has 36 ft of fence to put around a rectangular flower bed how long and how wide will the

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Length/width will be 9ft

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2 years ago

Estimate the quotient to the nearest whole number by using compatible numbers 32.44 ÷ 4.36

GarryVolchara [31]

I'm pretty sure its 7

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3 years ago

What is the slope of the line represented by the equation y=x/3-5

Nana76 [90]

Answer:

a. 1/3

Step-by-step explanation:

y=x/3-5 (rewrite x - term)

y = (1/3) x + 5

recall that in the slope-intercept form of a linear equation y = mx + b

m is the slope.

In our case, we can clearly see that slope m = (1/3)

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3 years ago

Kryptonite is a material found on the planet Krypton and has various effects, most importantly on Superman. The most common type

Rashid [163]

Answer:

The maximum amount of red kryptonite present is 33.27 g after 4.93 hours.

Step-by-step explanation:

dy/dt = y(1/t - k)

separating the variables, we have

dy/y = (1/t - k)dt

dy/y = dt/t - kdt

integrating both sides, we have

∫dy/y = ∫dt/t - ∫kdt

㏑y = ㏑t - kt + C

㏑y - ㏑t = -kt + C

㏑(y/t) = -kt + C

taking exponents of both sides, we have

$\frac{y}{t} = e^{-kt + C} \\\frac{y}{t} = e^{-kt}e^{C} \\\frac{y}{t} = Ae^{-kt} (A = e^{C})\\y = Ate^{-kt}$

when t = 1 hour, y = 15 grams. So,

$y = Ate^{-kt}\\15 = A(1)e^{-kX1}\\15 = Ae^{-k}$ (1)

when t = 3 hours, y = 30 grams. So,

$y = Ate^{-kt}\\30 = A(3)e^{-kX3}\\30 = 3Ae^{-3k}$ (2)

dividing (2) by (1), we have

$\frac{30}{15} = \frac{3Ae^{-3k}}{Ae^{-k}} \\2 = 3e^{-2k}\\\frac{2}{3} = e^{-2k}$

taking natural logarithm of both sides, we have

-2k = ㏑(2/3)

-2k = -0.4055

k = -0.4055/-2

k = 0.203

From (1)

$A = 15e^{k} \\A = 15e^{0.203} \\A = 15 X 1.225\\A = 18.36$

Substituting A and k into y, we have

$y = 18.36te^{-0.203t}$

The maximum value of y is obtained when dy/dt = 0

dy/dt = y(1/t - k) = 0

y(1/t - k) = 0

Since y ≠ 0, (1/t - k) = 0.

So, 1/t = k

t = 1/k

So, the maximum value of y is obtained when t = 1/k = 1/0.203 = 4.93 hours

$y = 18.36(1/0.203)e^{-0.203t}\\y = \frac{18.36}{0.203}e^{-0.203X1/0.203}\\y = 90.44e^{-1}\\y = 90.44 X 0.3679\\y = 33.27 g$

<u>So the maximum amount of red kryptonite present is 33.27 g after 4.93 hours.</u>

3 0

2 years ago

5b 2 −6b−2 is prime TURE OR FALSE!! 100 POINTS PLEASE HELP!!!!

Ivan

The given quadratic expression; 5b² -6b -2 is prime because the discriminant is not a perfect square.

<h3>What is the discriminant of the expression?</h3>

According to the task content; it is required to identify if the expression is prime.

On this note, it follows that the discriminant of the expression can be evaluated as follows;

= 36 -(4× 5 × -2)

= 76.

Hence, the expression is prime since 76 is not a perfect square.