The formula of simple interest is:
I=PRT
Where:
I stands for
InterestP stands for
Price (or Principle Amount)R stands for
RateT stands for
Time (in years)
I=PRT
=7000×0.062×1.5
(6.2%=

=0.062)
(18 months=12 months and 6 months=1.5 year)
=
$651
$7000+$651=$7651
By the end of 18 months, Mai has $7651 in her account