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Last month's solutions
Solution: Let n be the number of friends originally in the group. 800(n2) + 20n(n2) = 800n Therefore, n² – 2n – 80 = 0 The solutions of this equation are −8 and 10. Since a negative solution makes no sense for the number of people in a group, the number n of friends originally in the group was 10. 

Solution: Volume of the cylinder = (π r²)h = 8 π r² = π 72, 
Solution: Let x = pounds deposited in the investment account on January 1, 2001. Then, x(2^4) = 480 gives 16x = 480 and x = 30 pounds.
