"4 inches" is a length. "7676 square feet" is an area. "4 inches by 7676 square feet" describes a volume, which is equal to 2,558.67 cubic feet. (= 7676/3, because 4 in = 1/3 ft.) So your question is better put as "How many tons of crushed stone does it take to cover an area of 7676 square feet to a depth of 4 inches?"
Read On