If the price goes up by 3.17% then it has been multiplied by 1 plus 3.17%: that is, by 1.0317. Similarly it next went up by 1 plus 9.61%, that is, 1.0961. (Remember that % means divide by 100). So it went up overall by 1.0317 times 1.0961, which is 1 + x where you can compute x (it will be around 0.13 or thereabouts). The percentage increase is 100x %. You can check from the raw prices: increase is 71.25 - 63, which as a fraction of the original is (71.25-63)/63, then multiply by 100 to get it as a percentage. You should get the same answer in each case.