The rate of simple interest for first two years is 8% p.a., for the next 4 years, it is 10% p.a. and for the period beyond 6 years, it is 12% p.a. If a person gets ₹18358.60 as simple interest after 9 years, then how much money (in ₹)did he invest ?

19955

If Principal  = 100 then Interest = Rate  (R)× Time (T)

Interest for first 2  Years at 8% =  R× T =  8% × 2= 16%

Interest for next 4 Years at 10% =  R× T =  10% × 4= 40%

and Interest for next 3 Years at 12% =  R× T =  12% × 3= 36% 

⇒ Total Interest for 9 years =   16% + 40% + 36% = 92%

A.T.Q ,

Total Interest for 9 years = Rs 18358.60

⇒ 92% = 18358.60

⇒1% = 199.55

⇒100%= Rs 19955

ALTERNATE

total Interest =  8% × 2 +   10% × 4 + 12% × 3 = 16% + 40%+ 36% = 92%

ATQ,

92% of Principal = Rs 18358.60

⇒ P = Rs 19955