Question

A trust fund has $Rs.30,000$ that must be invested in two different types of bonds. The first bond pays $5$% interest per year, and the second bond pays $7$% interest per year. Determine how to divide $Rs.30,000$ among the two types of bonds. If the trust fund must obtain an annual total interest of
(a) $Rs.1800$
(b) $Rs.2000$

Answer 1

Given that first bond pays $5$% interest per year and second bond pays $7$% interest per year let the money invested in first bond be $x$ and in second bond be $y=30000-x$

therefore total interest $=(5/100\times x)+(7/100\times (30000-x\left)\right)=2100-0.02\times x$

a.)given total interest $=1800$

i.e. $2100-0.02x=1800$

therefore $x=15000,y=30000-x=15000$

b.)given total interest $=2000$

i.e. $2100-0.02x=2000$

therefore $x=5000,y=30000-x=25000$