A woman invested $1,000, part at 5% and the rest at 6%. Her total investment with interest at the end of the year was $1,054. How much did she invest at 5%?  Choose the correct choice from the following options.
A) $ 500  B) $ 600  C) $ 700  D) $ 900  E) $ 950

Rationale: et x be the portion invested at 5 % and let ( 1 - x ) be the rest which is invested at 6 % the question states that the return after 1 year is ( 1054 / 1000 ) - 1 = 0.054 = 5.4 % we want to find the dollar amount invested in x using our defined variables , put together the equation and solve for x ( the percentage of 1000 invested at 5 % ) 0.05 x + 0.06 ( 1 - x ) = 0.054 ( 0.05 ) x + 0.06 - ( 0.06 ) x = 0.054 - 0.01 x = - 0.006 x = - 0.006 / - 0.01 = 6 / 10 = 60 % so x = 60 % of the 1000 which is 600 answer : b
Answer: B