The average of and is 16. The average of and is 26. The average of , and is 20. What is the value of ?
Solution
Since the average of and is 16, then rac{a+b+c}{3}=16 and so . Since the average of and is 26, then rac{c+d+e}{3}=26 and so . Since the average of , and is 20, then rac{a+b+c+d+e}{5}=20. Thus, . We note that and so which gives .
Want a route through all this instead of an archive? The track
puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.