The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation? Choose the correct choice from the following choices:
A) 9  B) 8  C) 7  D) 6  E) 2
1 to 9 = 9 * 9= 
<gadget id="calculator">9 * 9</gadget>
<output>81</output>
81   1 to 5= 5 * 10= 
<gadget id="calculator">5 * 10</gadget>
<output>50</output>
50   5 to 9= 5 * 8= 
<gadget id="calculator">5 * 8</gadget>
<output>40</output>
40   5th= 50 + 40= 
<gadget id="calculator">50 + 40</gadget>
<output>90</output>
90 – 81= 9   9nswer: 9
<result>A</result>
The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation?