.
Fifteen litres of fuel containing 3.2% oil is available for a certain two-cycle engine.
This fuel is to be used for another engine requiring a 5.5% oil mixture. How many litres of oil must be added?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The basic equation is
= 0.055. (1)
To solve it, multiply both sides by (15 + v). You will get
15*0.032 + v = 0.055*(15+v),
0.48 + v = 0.825 + 0.055v,
v - 0.055v = 0.825-0.48,
0.945v = 0.345 ---> v = = 0.365.
Answer. 0.365 liters of oil must be added.
Be aware: Writing by josgarithmetic on this problem is absolutely wrong starting from his first equation.