Word Problem on Proportions

crappiefisher26

New member
Joined
Jul 23, 2006
Messages
49
Kevin earned $165 interest for 1 year on an investment of $1500. At the same rate, what amount of interest would be earned by and investment of $2500.

165/1500=2500/x

i then cross multiplied

1500 times 2500 and got 3,750,000

then got 3750000/165

x=22727.27273

would that be right? if not let me know what i did wrong so i can fix it, would x= simplify to $22,727
 

TchrWill

Full Member
Joined
Jul 7, 2005
Messages
856
Kevin earned $165 interest for 1 year on an investment of $1500. At the same rate, what amount of interest would be earned by and investment of $2500.

165/1500=2500/x

i then cross multiplied

1500 times 2500 and got 3,750,000

then got 3750000/165

x=22727.27273

would that be right? if not let me know what i did wrong so i can fix it, would x= simplify to $22,727
You started out right but got switched in mid stream.

Assuming simple interest, 166/1500 = x/2500

I'm sure you can take it from here.
 

Denis

Senior Member
Joined
Feb 17, 2004
Messages
1,634
crappiefisher26 said:
Kevin earned $165 interest for 1 year on an investment of $1500. At the same rate, what amount of interest would be earned by and investment of $2500.
165/1500=2500/x
i then cross multiplied
1500 times 2500 and got 3,750,000
then got 3750000/165
x=22727.27273
would that be right? if not let me know what i did wrong so i can fix it, would x= simplify to $22,727
Crappy, use a bit of common sense:
are you ready to pay me $22,727 in interest if I lend you $2,500 for a year :?: :shock:
 

Mrspi

Senior Member
Joined
Dec 17, 2005
Messages
2,128
crappiefisher26 said:
Kevin earned $165 interest for 1 year on an investment of $1500. At the same rate, what amount of interest would be earned by and investment of $2500.

165/1500=2500/x

i then cross multiplied

1500 times 2500 and got 3,750,000

then got 3750000/165

x=22727.27273

would that be right? if not let me know what i did wrong so i can fix it, would x= simplify to $22,727
You made a common mistake in setting up the problem. Your first fraction is

interest / investment
165 / 1500

Shouldn't the second fraction be set up the same way?

interest / investment
x / 2500

NOW the two fractions are equal, and you can proceed to solve by cross-multiplying:

165 / 1500 = x / 2500

1500x = 165(2500)

See if this gives you a more reasonable answer.
 
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