Coins are stacked one on top of the other to form a column. The first column has 12 coins and subsequent columns have 2 more coins than the previous one. Find the number of columns if total number of coins is 432. Choose the most appropriate option.
A) 27  B) 16  C) 15  D) 26  E) 11
Assume there are n columns. This forms an Arithmetic Progression with first term 12 and nth term (12+2*(n-1)). The average is (12+12+2n-2)/2 or (11+n) and total number of coins will be (11+n)*n = n2+11n-432=0 or (n+27)*(n-16)=0   n=16 or -27. Since n cannot be negative, n=16   Answer is 16
<result>B</result>
Coins are stacked one on top of the other to form a column. The first column has 12 coins and subsequent columns have 2 more coins than the previous one. Find the number of columns if total number of coins is 432.