Question

How long must $542 be invested at a rate of 7% to earn $303.52 in interest

Answer 1

The number of years that must be invested at  a rate of 7 % to earn$ 303.52 in interest is

    8 years

 calculation

• by use of  the formula       A = P (1+  rt)
•  where :  A  is the final amount  =  542 + 303.52  =$ 845.52

                   P  is the principal   money to be invested =  $ 542

                       r= rate= 7/100=0.07

                      t=  time required

=$ 845.52=$ 542( 1+  0.07 t)

• open the  bracket
• = $845.53= $542 + $37.94  t

• like terms  together

    =$  845.53 -$542  = $37.94 t

   =$303.52 =$37.94 t

• divide both  side by  $37.94

  =  $303.52/ $   37.94  =  $37.94t/$37.94

  t=  8 years