The average of 13 numbers is 60. Average of the first 6 of them is 57 and that of the last 8 is 61. Find the 8th number?  Answers:
A) 46  B) 48  C) 50  D) 52  E) 54
Sum of all the 13 numbers = 13 * 60= 
<gadget id="calculator">13 * 60</gadget>
<output>780</output>
780   Sum of the first 6 of them= 6 * 57= 
<gadget id="calculator">6 * 57</gadget>
<output>342</output>
342   Sum of the last 8 of them= 8 * 61= 
<gadget id="calculator">8 * 61</gadget>
<output>488</output>
488   So, the 8th number= 342 + 488 - 780= 
<gadget id="calculator">342 + 488 - 780</gadget>
<output>50</output>
50.   ANSWER:50
<result>C</result>
The average of 13 numbers is 60. Average of the first 6 of them is 57 and that of the last 8 is 61. Find the 8th number?