Math word problem

Question

A total of $11,000 was invested. Part of the $11,000 was invested at 4% and the rest was invested at 7%. If the investments earn $680 per year, how much was invested at each rate

Answer 1

Problems of this kind are all very similar. Study of examples in a typical textbook would reveal the strategy, which is, basically, to split the money into two parts: 4x inv. at 4%, $11,000 - x inv. at 7%.

 

You then write the total interest equation: 0.04x + 0.07(11,000-x) = 680.

 

The third step is to solve for x.