The average of 6 observations is 15. A new observation is included and the new average is decreased by 1. The seventh observation is?  Choose one: A) 1 B) 8 C) 5 D) 6 E) 7
Let seventh observation = X.   Then, according to the question we have   =&gt; (90 + X) / 7 = 14   =&gt; X = 8   Hence, the seventh observation is 8   ANSWER:8
<result>B</result>
The average of 6 observations is 15. A new observation is included and the new average is decreased by 1. The seventh observation is?