brassy333 Posts: 1, Reputation: 1 New Member #1 May 21, 2009, 05:26 AM
How do I write the equation?
Helen Weller invested $10,000 in an account that pays 10% simple interest. How much additional moneymust be invested in an account that pays 13% simple interest so that the average return on the two investments amounts to 11%? I know the answer is$5,000.00 but I am unsure how to set up the problem to show that solution. Could you help me?
 Unknown008 Posts: 8,076, Reputation: 723 Uber Member #2 May 21, 2009, 08:07 AM

Ok, let's first give the amount a name, say 'x'

(13&#37; of x) + (10% of 10000) gives (11% of x + 10000) where x+10000 is the total sum.

So, in numbers;

$\frac{13x}{100} +\frac{10(10000)}{100} = \frac{11(x+10000)}{100}$

When you simply, solve for x and you're done. Post back if you have any difficulties.

Hope it helped! :)
 Perito Posts: 3,139, Reputation: 150 Ultra Member #3 May 21, 2009, 08:09 AM
$10,000 invested in an account that pays 10&#37; simple interest. How much additional money must be invested in an account that pays 13% simple interest so that the average return on the two investments amounts to 11%? I know the answer is$5,000.00
$10000 x 0.10 =$1000 is the annual interest at 10% on $10,000 Let A be the amount that's invested at 13% The amount earning interest at 10% plus the amount that's invested at 13% equals the two amounts as if they had been invested at 11%. This is the equation that results. ($10000 x 0.10) + (A x 0.13) = (\$10000 + A) x 0.11

We need to solve for A and check that it's correct by substituting back into the equation.

I see that Unknown008 beat me to the punch.

 Question Tools Search this Question Search this Question: Advanced Search

## Check out some similar questions!

Hi, How do you write an equation for this sequence whose difference increases by two each time? 10, 12, 16, 22, 30

Write the balance equation [ 3 Answers ]

Could you please help me to complete this equation , I get the major product but I didn't how to write others.. :confused: 1- Al^3+ + NH4Cl + 3NH4OH... > Al(OH)3 + 2- Ni^2+ + NH4Cl + NH4OH + Na2S... > NiS + 3- Ca^2+ + NH4Cl + NH4OH + (NH4)2CO3... > CaCO3 +

Write the balance equation [ 5 Answers ]

I tried to solve my homework , but I face some problem Im not sure about it and another I can't solve it.. Im not sure about the solve , could you check if it is right or wrong 1- (Salt + dil. HCl) with Carbonate CO3^2- + 2HCl -----> CO2 + H2O+ 2Cl^-

I'm confused on how to write a equation [ 1 Answers ]

The sum of a number, times itself equals 36. Is this an algebraic relationship?

I am racking my brains... I need help on figuring out how to write an equation of the line with x-intercept (-6,0) and y intercept (0,-1) Please help me understand how to get this question answered and please show me step by step I think this is how to do it... but am not sure... find...