Problema Solution
The water level of a swamp rises 5/3 inches every time it rains. On every day that it doesn't rain, the water level falls 1/6 inch due to evaporation. If it rained 15 days this month and did not rain the other 15 days, how many inches has the water level risen since the beginning of the month?
Answer provided by our tutors
let the water level at the beginning of the month be: x inches
it rained 15 days this month thus the water level went up by 15*(5/3) inches
it did not rain the other 15 days thus the water level went down by 15*(1/6) inches
the water level at the end of the month will be: x + 15*(5/3) + 15*(1/6) inches
how many inches has the water level risen since the beginning of the month?
the water level at the beginning of the month - the water level at the end of the month
x + 15*(5/3) + 15*(1/6) - x = (15*5)/3 + 15/6 = 25 + 5/2 = 27.5 in
the water level has risen by 27.5 inches since the beginning of the month.