1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Setler [38]
3 years ago
8

Olcquations

Mathematics
1 answer:
zaharov [31]3 years ago
8 0

Answer:

  • $600 at 8%
  • $2400 at 3%

Step-by-step explanation:

You have the right numbers, but the wrong accounts.

__

Let x represent the amount invested at 8% (the highest rate). Then the total interest is ...

  .08x +.03(3000 -x) = .04(3000)

  .05x = .01(3000) . . . . subtract .03(3000)

  x = 3000/5 = 600

Matthew invested $600 at 8%, $2400 at 3%.

_____

<em>Comment on checking your answer</em>

You may notice that the overall interest rate is 4%, closer to 3% than to 8%. That means more of the money must be invested at 3% than at 8%.

You might be interested in
the half-life of chromium-51 is 38 days. If the sample contained 510 grams. How much would remain after 1 year?​
madam [21]

Answer:

About 0.6548 grams will be remaining.  

Step-by-step explanation:

We can write an exponential function to model the situation. The standard exponential function is:

f(t)=a(r)^t

The original sample contained 510 grams. So, a = 510.

Each half-life, the amount decreases by half. So, r = 1/2.

For t, since one half-life occurs every 38 days, we can substitute t/38 for t, where t is the time in days.

Therefore, our function is:

\displaystyle f(t)=510\Big(\frac{1}{2}\Big)^{t/38}

One year has 365 days.

Therefore, the amount remaining after one year will be:

\displaystyle f(365)=510\Big(\frac{1}{2}\Big)^{365/38}\approx0.6548

About 0.6548 grams will be remaining.  

Alternatively, we can use the standard exponential growth/decay function modeled by:

f(t)=Ce^{kt}

The starting sample is 510. So, C = 510.

After one half-life (38 days), the remaining amount will be 255. Therefore:

255=510e^{38k}

Solving for k:

\displaystyle \frac{1}{2}=e^{38k}\Rightarrow k=\frac{1}{38}\ln\Big(\frac{1}{2}\Big)

Thus, our function is:

f(t)=510e^{t\ln(.5)/38}

Then after one year or 365 days, the amount remaining will be about:

f(365)=510e^{365\ln(.5)/38}\approx 0.6548

5 0
3 years ago
Four-thirds times the sum of a number and 8 is 24. What is the number?
schepotkina [342]

Answer:

D, 10.

Step-by-step explanation:

10+8=18 4/3x18=24

7 0
3 years ago
Read 2 more answers
Your friend is 5 years less then half her mom's age. your friend is 15 years old. how is the mother.
Digiron [165]
The mother is 25. i think
4 0
3 years ago
Read 2 more answers
I WILL GIVE YOU 80 POINTS BUT I NEED IT TODAY ONLY NEED TO ANSWER SIX AND SEVEN
Viefleur [7K]
Hope this helps! Mark me Brainliest plsssss

3 0
1 year ago
There are 9 1/5 gallons of water in Alan’s fish tank. If Alan adds 9 3/5 gallons more, how many gallons will there be in all?
cupoosta [38]
9 1/5 + 9 3/5 = 18 4/5 gallons
7 0
3 years ago
Other questions:
  • How many dots would be in the 50th figure?
    8·2 answers
  • Solve the system by substitution. <br> 7x-3y=-25 <br> 4x+5=y <br><br> Simplify<br> ( , )
    9·1 answer
  • Express 4.4 as a percent.
    14·2 answers
  • the half-life of isotope X is 2.0 years. How many years would it take for a 4.0mg sample of X to decay and have only 0.50 mg of
    13·1 answer
  • Nancy started the year with $435 in the bank and is saving $12 a week. Shane started with $1027 and is spending $25 a week. When
    10·1 answer
  • What is the area of the figure to the nearest hundredth renter the answer in the box 2yd 4yd
    9·1 answer
  • If the sides of a right triangle are 6 feet and 8 feet, what is the length of the hypotenuse? *
    13·2 answers
  • Adelphi is 34.3 miles east of sterling. The distance between Adelphi and sterling is
    14·2 answers
  • A ladder is propped against the side of a building making a 30 degree
    7·1 answer
  • What is the quotient of (x cubed 3 x squared minus 4 x minus 12) divided by (x squared 5 x 6)?
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!