The answer is yes!!
I have been making jam, quite successfully if I do say so myself, for over 40 years now. I am self- taught. That is, I read the directions in the pectin package and follow them to the letter - as they tell you that you must - or they will not guarantee the results
We are having a crowd for dinner on Sunday - so I bought a large amount of frozen lasagna - and needed to find room for it in the freezer. I had a large amount of frozen raspberries in my freezer, so I decided to take them out and make jam - since we were pretty much out of jam - having given most of it away as gifts for colleagues of mine. I am in the habit of buying raspberries and strawberries whenever they are going for a good price - and then I freeze them and mostly make jam in the wintertime - a much better time than summer for making jam, by the way.
Feeling industrious and virtuous, I proceeded to mash the raspberries and measure them out - 5 cups of fruit for 7 cups of sugar. I carefully measured out 7 cups of fruit, added the pectin, gave it a good stir - and realized that the 7 went with the sugar, not the fruit!!
I was loathe to toss it. Loathe to consign myself to an absurdly large batch of raspberry syrup - we'd never eat that many pancakes in a century, let alone a lifetime!!
As a teacher, I am always telling my students that knowledge is power - all knowledge is helpful - all knowledge is useful. I said to myself, "Is this really true?' Then I said to myself, "5 cups of fruit to 7 cups of sugar is the same ratio as 7 cups of fruit to how many cups of sugar?" Buffy D. would have been prouder of me if I'd used an X for the unknown, but I was satisfied with my efforts.
A little math later, I figured out that 5 cups of fruit is to 7 cups of sugar as 7 cups of fruit is to 9.8 cups of sugar. But then I remembered that there was another element to this equation: the pectin!
Not to be thwarted, I opened another package of pectin and measured it out - it equaled 5 tablespoons. So then the question became, How many tablespoons of pectin did 7 cups of fruit need? I was stumped - math is not my forte. I went out to Harry's office - and he solved the equation rather easily. He said, "If 5 tablespoons of pectin is used for 5 cups of fruit, then the formula must be one tablespoon for each cup of fruit." Thus it followed that I needed 7 tablespoons of pectin - so I added two more to the batch.
This story has a happy ending. This "altered" batch of jam turned out just fine - just like all the others. So much for Sure-Jell telling you that if you alter the measurements, they can't guarantee your success!
I feel like a regular genius tonight!!