what is the percent change from 40 to 45
E = change in quantity demanded Change in Price. E = 11% 28% E = 39%. Midpoint Method. Calculating percentage change as done above is often sufficient. However, you may notice that if we calculate the percentage change in price as (45 - 40)/40 x 100 we find that the percentage change is (-12.5 percent).In other words, it makes a difference if we look at the change as a rise or a fall; this is end-point problem .ercentage change in quantity: Percentage change in income: Example. Suppose the price of Atlanta Thrashers tickets falls from $45 to $40 and the quantity demanded for tickets increases from 18,000 tickets to 23,000 tickets.