c. Dagwood invested certain amount in three different schemes A, B and C with rate of interest 10% p.a, 12% and 15% p.a respectively, I the total total interest accrued in one yer was Tk, 3200 and the amount invested in Scheme C was 150% of the amount invested in Scheme A and 240% of the amount invested in Scheme B, what was the amount invested in Scheme B?

Let, the amount invested in Scheme B = Tk. 100x 

So, the amount invested in Scheme C= Tk.$(100x \times 240\%)=Tk. 240x$

Here, the amount invested in Scheme C = 150% of the amount invested in Scheme A

$$\begin{gathered} \Rightarrow Tk. 24x= 150\times \frac{A}{100} \\ \Rightarrow A=TK. \frac{24,000}{150}=TK. 160x \end{gathered}$$

So, the amount invested in Scheme A= Tk. 160x

Now, Interest from Scheme A= Tk. $(160x \times 10\%) = Tk. 16x$

Interest from Scheme B= $Tk. (100x \times 12\%) = Tk.12x$

Interest from Scheme C = Tk.$(240x\times 15\%) = Tk.36x$

According to the question, 

$$\begin{gathered} 16x+12x+36x=3,200 \\ \Rightarrow 64x=3200 \\ \Rightarrow x=\frac{3200}{64} \\ \Rightarrow x=50 \\ \Rightarrow 100x=50\times 100 \\ \therefore 100x=5,000 \end{gathered}$$

So, the amount invested in Scheme B = Tk. 5000 ans.