Answer:
Step-by-step explanation:
Here we use the formula for simple interest as
Simple interest = [tex]\frac{PNR}{100}[/tex]
P stands for principal, N = no of years and r = rate of interest.
i)Here [tex]P = 800: n=5 \\ r= 5 p.c\\SI =\frac{800(5)(5)}{100} =200[/tex] dollars
ii) Here [tex]P = 2500: n=1 and r= ?: Si = 70[/tex]
[tex]\frac{2500(1)(r)}{100} =70\\r=\frac{70}{25} =2.8[/tex] percent
iii) [tex]P = 100: n=1 and r= ?: \\P+Si = 106.50\\Interest = 106.50-100\\=6.50[/tex]
Thus simple interest = 6.50
[tex]\frac{100(1)(r)}{100} =6.50\\r = 6.5[/tex]
Option A is right