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Jlenok [28]
2 years ago
6

A math test has 10 multiple-choice questions, each with 3 answers to choose from. If a person taking this test were to guess on

every question, what is the probability that they will receive a grade of 70 or above?
1.967%
2.057%
4.286%
1.626%​
Mathematics
1 answer:
NeTakaya2 years ago
4 0
2.057% i think is the answer
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movie tickets cost $9.25 each and a large order of popcorn costs $7.75 what is the total cost of 5 movie tickets and a large ord
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The answer would be 54 dollars
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3 1/4 x 5/8? that is, 3 and 1/4 times 5/8
maw [93]

Answer:

first make mixed

13/4 x 5/8

just multiply the numerator with numerator and denominator with denominator

13x5=65

4x8=32

65/32 or 2 1/32

Step-by-step explanation:

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A cone ha a volume of 27 pi cm cubed and a radius of 3 cm what is the height of the cone
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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>

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John is 12 years older than Miles. Five years ago, John was two times as old as Miles was back then. How old are John and Miles
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Answer:

John is 29, Myles is 17.

Step-by-step explanation:

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