Using the new unit you have defined, rewrite the debt for years 1900, 1930, 1960, and 2000.

Suppose that y varies directly with x and y=10 when x=20. What is y when x=15

Likurg_2 [28]

Answer:

y=kx

subst y=10 and x=20 into the above

10=k20

k=10/20

k=1/2

therefore relationship: y=1/2x

subst x=15 into the relationship

y=1/2(15)

y=7,5

Step by step explanation:

Step 1: when they say y varies directly with x they mean y is proportional to x
step 2: so y=kx where k is the constant
step 3: is to substitute y=10 and x=20 into the above equation y=kx
step 4: you will end up with 10=k20 then divide both sides by 20 so that k becomes the subject of the formula 
step 5: your answer from the above will be k=10/20 so the relationship is y is directly proportional to 1/2 x what you did here is that you substituted k for 1/2 in the equation in step 3
step 6: is to finally substitute x=15 into the equation y=1/2x to finally get your answer y=7,5.

4 0

3 years ago

A cup of coffee with temperature 155degreesF is placed in a freezer with temperature 0degreesF. After 5 minutes, the temperatur

Leviafan [203]

Answer:

45.50° F

Step-by-step explanation:

As per Newton's law,

$T(t) = T_{s}+(T_{0} + T_{s})e^{-kt}$

When T(t) is the final temperature

$T_{s}$ = Temperature of surrounding

$T_{0}$ = Initial temperature

t =duration of cooling

k = constant

$103=0+(155-0)e^{-k\times 5}$

$103=155e^{-5k}$

Now take natural log on both the sides

$ln(103)=ln(155e^{-5k})$

$ln(103)=ln(155)+ln(e^{-5k})$

$ln(103)=ln(155)=-5k$

4.6347 - 5.0434 = -5k

$k=\frac{0.40872}{5}$

k = 0.0817

$T(t)=0+(155-0)e^{(0.0817\times 15)}$

= $155e^{-1.226}$

= 155 (02935)

= 45.49 ≈ 45.50° F

8 0

3 years ago

Can someone HELP and Explain. Denise just bought a new house and she is choosing paint colors. There is an 80% chance she will u

aniked [119]

Well I don't know if I would recommend the blue I would actually would go for the yellow because it is my favorite color so ya she should pick yellow.

6 0

3 years ago

Read 2 more answers

Maria stated that 5/6 is between 4/5 and 6/7

Vlada [557]

Answer:

It's true, if that's what your asking.

Step-by-step explanation:

5/6 = 0.833 to 3 sig.fig.

4/5 = 0.800 to 3 sig.fig.

6/7 = 0.857 to 3 sig.fig.

0.833 is more than 0.800 and less than 0.857.

3 0

3 years ago

What is the surface area of a mini basketball with a circumference.of 25 and radius of 4

Nonamiya [84]

The formula to find the surface area of a sphere is A=4(3.14)r². So if you plug in the data you would get,
A=4(3.14)4²
A=(12.56) (16)
A=200.96
You mught want to check over it so you will be able to solve it for yourself the next time you have this question.

4 0

3 years ago