Question

mudrik installed a device on his car that guaranteed to increase his gas mileage by 15% .He currently gets 22 miles per gallon .How much will the gas mileage increase after installing the device please help

Answer 1

According to the advertising, Mudrik expects his gas mileage
to increase by

           (0.15) x (22) = 3.3 mpg ,

    to     (22) + (3.3) = 25.3 mpg .

But to answer the question exactly as you asked it,
I would predict that the change in the gas mileage
after installing the device will be insignificant, and
that the change is equally likely to be either an
increase or a decrease.

If such a device existed, it would already be standard
equipment on every car that's sold.