Add 72, 75, and 83, which equal 230. Then, since there are three values, you divide the total (230) by 3, which would equal 76.6 (cont), therefore meaning they can only raise their average (using the three tests, from a base grade of 0) to a 76.6 percent (or 77 if teacher rounds grade)
No of people not from their neighborhood=25-20=5 total contact s=25 therefore probability to call a person not from his neighborhood=5/25=1/5 therefore P=1/5
