The average of a certain set of 'b' numbers is 'a', and the average of a ce1tain set of 'a' numbers is 'b'. What is the average of all the numbers taken together? |
2b ÷ (a + b) 2ab ÷ (a + b) (a + b) ÷ 2ab 2a ÷ (a + b) |
2ab ÷ (a + b) |
Average of set of b numbers = a Average of set of a numbers = b Average = Total sum of values ÷ Number of values Sum of set of b numbers = Average × Total values Sum of set of b numbers = a × b = ab Sum of set of a numbers = b × a = ba Total Sum of all numbers = ab + ba = 2ab Total values = a + b Average of all numbers = 2ab ÷ (a + b) |