n a certain city, the daily use of water (in hundreds of gallons) per household is a continuous random variable with probability density function

f(x) = 0.15e^{- 0.15x}(if x > 0, otherwise f(x) = 0).

Find the probability (to the nearest percent) that a household chosen at random will use at least 100 gallons of water per day.

1) 14%

2) none of these

3) 86%

4) 100%