What is the interest earnt on a $5000 investment at 6.4% p. a. after 3 years if interest is compounded weekly?

Let's assume there are 52 weeks in a year,
so we have , rate= 6.4/52= 0.123%
now ,
c.i = 5000[(1+0.123/100)^3×52 -1]
= $1056.911
took me a while

Rounding decimals is very similar to rounding other numbers. if the hundredths and thousandths places of a decimal is forty-nine or less, they are dropped and the tenths place does not change. for example, rounding 0.843 to the nearest tenth would give 0.8. , your welcome !