The average of #a# and #b# is 6 and the average of #a,b,# and #c# is 11. What is the value of #c#?
1 Answer
Jun 12, 2017
Explanation:
#(a+b)/2=6larrcolor(blue)" calculating the average"#
#rArra+b=2xx6=12larrcolor(blue)" cross-multiplying"#
#"now " (a+b+c)/3=11#
#rArra+b+c=33#
#"using " a+b=12larr" from above"#
#rArr12+c=33#
#"subtract 12 from both sides"#
#cancel(12)cancel(-12)+c=33-12#
#rArrc=21#
