Question

The air in a container has a constant temperature of 43.7° F. The air is then cooled at a rate, measured in degrees Fahrenheit, represented by the function R(x) = 1.4x - 1, where x is the time in hours.

Which function best describes A(x), the temperature of the air over time?

A(x) = 44.7 - 1.4x

A(x) = 42.7 + 1.4x

A(x) = 43.7(1.4x) - 43.7

A(x) = 1.4x - 44.7

Answer 1

Welcome to Openstudy

Answer 2

Thank you :)

Answer 3

you want to find A(x)

Answer 4

I have no clue of how to write the function

Answer 5

i can solve this using calculus, but are you learning calculus?

Answer 6

no

Answer 7

may I ask where did you get this question.

Answer 8

study island

Answer 9

make sure I am copying this correctly
the rate at which it is cooling is
R(x) = 1.4*x - 1

Answer 10

yes

Answer 11

I am asking all these questions because the question seems odd. None of the choices match what I think is the correct answer

Answer 12

that is what is throwing me off...

Answer 13

This is one way to solve this, but it doesn't match your choices.

Using calculus we can integrate the rate R(x) to get the temperature

A(x) = integral (1.4x - 1) dx

A(x) = 1.4 x^2/2 -x + C

A(0) = 43.7

A(x) = 1.4 x^2/2 - x + 43.7

@ganeshie8 maybe you could look this over

Answer 14

that would make sense but i am limited to their choices.

Answer 15

If i had to guess i would pick a)

Answer 16

since a) is the only option with a negative slope or rate (since it is cooling)

Answer 17

is it possible for you to upload the question, so I can see the original

Answer 18

if you can take a screenshot

Answer 19

the correct answer turned out to be B

Answer 20

Lynn works at a retail department store where she has a coupon to receive $10.00 off her next purchase. She also receives a 31% employee discount. If p represents the amount of her purchase, which function applies the coupon and discount so that Lynn pays the lowest amount?

D(p) = 0.69p - 10

D(p) = 0.31(p - 10)

D(p) = 0.31p - 10

D(p) = 0.69(p - 10)
can you make any sense out of this one?

Answer 21

b) is wrong.
they did A(x) = A(0) + R(x)

Answer 22

which doesn't make sense.

Answer 23

yes we can do the coupon problem :)

Answer 24

im starting to think study island is rigged against me...

Answer 25

i would think the first option

Answer 26

There are two ways she can pay for the item
Option 1:
she can first apply the ten dollar coupon, then the 31% employee discount:
(p - 10)* ( 1 - .31) = (p - 10) * .69 =

Option 2:
first apply the 31% employee discount, then ten dollar coupon:
p( 1 - .31) - 10 = .69*p - 10


Let's plug in p = 100 to see which comes out less.


option 1:
(100 - 10) * .69 = 62.1


option 2:
.69 * 100 - 10 = 59

Answer 27

so option 2 is less

D(p) = .69p - 10

Answer 28

which corresponds to a) in your multiple choices

Answer 29

thank you :)

Answer 30

is it correct ?

Answer 31

how about this one?
Currently, there are 93 bald eagles in Forest National Park. Bald eagles are an endangered species, and the population of bald eagles is decreasing by 7% every year. Which of the following functions represents the number of bald eagles in Forest National Park in t years?

B(t) = 93(0.93)t
B(t) = 93(1.07)t
B(t) = 93(-0.93)t
B(t) = 86.49t

Answer 32

oh i see option 1 is equivalent to
(p - 10)* ( 1 - .31) = (p - 10) * .69 = = .69*p - 10*.69 = .69p - 6.9

option 2 is .69p - 10

so you can see option 2 is lower

Answer 33

we can use the function
y = 93 ( 1- r / 100)^t ,
where r is given as a percent , t is in years, y represents the remaining eagles