Answer:
<em>There are 21 jelly beans in the jar.</em>
Step-by-step explanation:
Suppose, the number of jelly beans in the jar is 
Two were off by 2, two were off by 3, two were off by 4. That means, the six guessed number will be: 
Given that, Alice guessed 25; Betty, 18; Clare, 23; Dotty, 19; Edith, 24; and Fran, 17.
So, the sum of all six guessed number will be: 
Thus, the equation will be..........

So, the number of jelly beans in the jar is 21.