The average of 15 result is 55. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th result?
Choose the correct choice from the following answers
A) 760 B) 720 C) 700 D) 786 E) 797
Sum of all the 13 results = 15 * 55= 
<gadget id="calculator">15 * 55</gadget>
<output>825</output>
825   Sum of the first 7 of them= 7 * 57= 
<gadget id="calculator">7 * 57</gadget>
<output>399</output>
399   Sum of the last 7 of them= 7 * 61= 
<gadget id="calculator">7 * 61</gadget>
<output>427</output>
427   So, the 8th number= 825 + 399 - 427= 
<gadget id="calculator">825 + 399 - 427</gadget>
<output>797</output>
797.   797
<result>E</result>
The average of 15 result is 55. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th result?