Question 541630
partI	x	8	%						
part II	y 	6	%						
part III	z	9	%						
Total Investment=$			140000						
Total interest from all =$			10440						
Interest from Part I is			2	times interest from Part II					
									
Interest from 		part II	=	0.06	y 				
Interest from  		partI	=	0.08	x	=			
Interest from 		part III=	0.09	z				
0.08	x	=	2	*	0.06	y 			
0.08	x	=	0.12	y 					
x=	1.5	y 							
0.06	y 	+	0.08	x	+	0.09	z	=	10440
But	0.08	x	=	0.12	y 				
0.06	y 	+	0.12	y 	+	0.09	z	=	10440
0.18	y 	+	0.09z	=	10440		-------------- 1		
									
Investment at									
x+y+z=	140000								
1.5	y+  	1	y	+	1	z	=	140000	
2.5	y 	+	1	z	=	140000	--------------2		
									
0	y 	+	0.09	z	=	10440	.............1		
2.5	y 	+	1	z	=	140000	.............2		
Eliminate 	z								
multiply (1)by 		1							
Multiply (2) by		-0.09							
0.18	y 		0.09	z	=	10440			
-0.23	y 	+	-0.09	z	=	-12600			
Add the two equations									
-0.04	y 				=	-2160			
/	-0.04								
y 	=	48000.00							
plug value of 			y 	in (1)					
0.18	y 	+	0.09	z	=	10440			
8640		+	0.09	z	=	10440			
			0.09	z	=	10440		-8640	
			0.09	z	=	1800			
				z	=	20000.00			
									
x+y+z=	140000								
									
x=	140000	-(	48000	+	20000	)			
x=	72000								
									
CHECK									
									
	amount  	Rate		Interest  					
x =	72000	8	%	5760					
y=	48000	6	%	2880					
z=	20000	9	%	1800					
Total  	140000			10440					
									
m.ananth@hotmail.ca