Answer:
20 cents
Step-by-step explanation:
Possible coins in grandfather's pocket include : nickel, dime, quarter
A nickel = 5 cents
A dime = 10 cents
A quarter = 25 cents
First combination= nickel+dime+quarter+quarter
Second combination=nickel+quarter+quarter+quarter=
Third combination= dime+quarter+quarter+quarter
Third combination=quarter+quarter+quarter+quarter
4th combination = nickel + nickel+dime+quarter
5th combination= nickel +nickel+nickel+dime
6th combination =nickel+nickel+nickel+quarter
7th combination= nickel + nickel + nickel +nickel
8th combination = dime + dime +quarter +nickel
9th combination = dime +dime+dime+quarter
10th combination =dime+dime+dime+nickel
11th combination=dime+dime+dime+dime
If Grandpa offers to give you the coins if you are able to guess the amount within ten cents, then all coins are below ten cents and all coins are nickels = 4 nickels ×5 = 20 cents