help!

[cooljam250]

hey guys,

does anyone know how to solve these two questions?

1. The price of a left-handed widget increased 20% in 1981 and 10% in 1982. By approximately what percent would the price at the end of 1982 have to be decreased to restore the price of the widget to its pre-1981 price?

a) 40%
b)35%
c)30%
d)26%
e)24%



2. Particia invested a sum of money at an annual simple interest rate of 10 1/2% (10 and a half percent). AT the end of 4 years the amount invested plus interest earned was $781.00. What was the dollar amount of the original investment?

a)$231.84
b)$318.16
c)$550.00
d)$750.00
e)$781.84


ANS #1 = 24%

ANS #2=$550.00


Thank you!

[maxim730]

1) I just used a #

x = 100

1981 = 1.2(x) = 1.2(100) = $120

1982 = 1.1(1.2x) = 1.1(120) = $132

Pre 1981 price, i.e. to x = (132-100) / (132) = .24 = 24%

[thankont]

careful here because they want simple interest and not compound
original amount -->x
simple interest after 4 yrs. -->4x(0.105) = 0.42x
so we have after 4 yrs. --> 1.42x = 781 => x = 550

[cooljam250]

thanks guys, i understand it now :!: