In making a large pot of chili for a family reunion, you find that you have to add 1 onion to your pot of chili that already has 5 onions mixed in it to notice a difference. according to weber’s law, how many onions would you have to add to notice a difference if you are making twice as much chili with 10 onions?

2

Explanation:

Weber's law of noticeable difference states that  to observe a noticeable variation in sensory experience  we need to increase the intensity beyond Difference threshold.

Here also for family reunion difference threshold is 5 onions so we need to add beyond it i.e. one onion more to get the  noticeable change.

Thus for twice the chili with 10 potatoes we need to add 2 more.