Question: The average amount with a group of seven numbers is Rs. 30. If the newly joined member has Rs. 75 with him, what was the average amount with the group before his joining the group?
Options:
(A) s. 25.6
(B) s. 45/2
(C) s. 16.6
(D) s. 26
(E) s. 25/2 Let's think first. Some random reasoning:
Total members in the group = 7
Average amount = Rs. 30
Total amount with them = 7 * 30 = Rs. 210
One number has Rs. 50. So, the amount with remaining 6 people = 210 - 75 = Rs. 135
The average amount with them = 135/6 = Rs. 45/2 The final answer: (B).