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3 years ago

Jack is 4 times as old as lacey. 7 years ago the sum of their age was 61. how old are they now?

Mathematics

1 answer:

BaLLatris [955]3 years ago

7 0

I am guessing Jack is 51 and Lacey is 17.

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Point A is 4 units away from the origin along the x-axis, and is 7 units away along the y-axis. Which of the following could be

siniylev [52]

Answer: C (4,7)

Points are labeled as (x,y)

If the unknown point is 4 units away from the origin on the x axis, x will be 4

If the unknown point is 7 units away from the origin on the y axis, y will be 7

Therefore (4,7)

6 0

2 years ago

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If y = kx, what is the value of x if y = 0.33 and k = 1/4? A) 0.08 B) 0.33 C) 0.50 D) 1.32

Vladimir79 [104]

y = kx
x = y/k if y = 0.33 and k = 1/4
x = 0.33/0.25
x = 1.32

answer
D) 1.32

7 0

3 years ago

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9. Determine how long it takes for 80% of the material to decay.

Vilka [71]

Using an exponential function, it is found that it takes 18.6 days for 80% of the material to decay.

The amount of a substance after t days is modeled by:

$A(t) = A(0)e^{-kt}$

In which:

k is the decay rate, as a decimal.

A(0) is the initial amount.

The half-life is of 8 days, hence $A(8) = 0.5A(0)$ , and this is used to find k.

$A(t) = A(0)e^{-kt}$

$0.5A(0) = A(0)e^{-8k}$

$e^{-8k} = 0.5$

$\ln{e^{-8k}} = \ln{0.5}$

$-8k = \ln{0.5}$

$k = -\frac{\ln{0.5}}{8}$

$k = 0.08664339757$

Hence:

$A(t) = A(0)e^{-0.08664339757t}$

The time it takes for 80% of the material to decay it t for which $A(t) = 0.2A(0)$ , hence:

$0.2A(0) = A(0)e^{-0.08664339757t}$

$e^{-0.08664339757t} = 0.2$

$\ln{e^{-0.08664339757t}} = \ln{0.2}$

$-0.08664339757t = \ln{0.2}$

$t = -\frac{\ln{0.2}}{0.08664339757}$

$t = 18.6$

It takes 18.6 days for 80% of the material to decay.

To learn more about exponential functions, you can take a look at brainly.com/question/24906920

5 0

3 years ago

If the lengths of the sides of a triangle measure 5/4 m 3/2 m and 1/8 m, determine its perimeter.

atroni [7]

Answer:

23/8

Step-by-step explanation:

To find the perimeter of the triangle we need to add all the sides. Since the sides all have different denominators in their fractions, first we need to make the denominator the same.

5/4 = 10/8

3/2 = 12/8

1/8 = 1/8

Then we just add the numerators and keep the denominator the same, which gets us 23/8 meters. Since 23/8 can be simplified, that's the answer.

5 0

3 years ago

Help

Dafna11 [192]

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7 0

3 years ago

Read 2 more answers