A whale goes on a feeding frenzy that lasts for 9 hours. For the first hour he catches and eats x kilos of plankton. In every hour after the first, it consumes 3 kilos of plankton more than it consumed in the previous hour. If by the end of the frenzy the whale will have consumed a whopping accumulated total 450 kilos of plankton, how many kilos did he consume on the sixth hour?	Answers.
A) 38	B) 47	C) 50	D) 53	E) 62
Suppose food eaten in first hour : x   The AP is : x, x+3, x+6, .... [Number of terms 'n' = 9]   Therefore,   9/2[2 x + (9-1)*3] = 450.   Solving for x, x = 38.   Now, 6th term will be : x + (6-1)*d = 38 + 5*3= 
<gadget id="calculator">38 + 5*3</gadget>
<output>53</output>
53.   Hence 53 !!
<result>D</result>
A whale goes on a feeding frenzy that lasts for 9 hours. For the first hour he catches and eats x kilos of plankton. In every hour after the first, it consumes 3 kilos of plankton more than it consumed in the previous hour. If by the end of the frenzy the whale will have consumed a whopping accumulated total 450 kilos of plankton, how many kilos did he consume on the sixth hour?