What do you understand by averages?
Average is sum of all observations upon number of observation. For eg. Kripa had monthly salary of 20000 and krishna of 40000. There average would be 40000+20000 i.e. sum 60000 upon 2. Answer is 30000. In this question there were 2 observation.
some basic formulas
Sum of first n natural no. = n(n+1)/2
Sum of first n odd no. = n square
Sum of first n even no.= n(n+1)
sum of square of first n natural no. = n(n+1)(2n+1)/6
sum of cube of first n natural no= (n(n+1/2))whole square
- If n is odd: The average of n consecutive numbers, consecutive even numbers or consecutive odd numbers is always the middle number.
- If n is even: The average of n consecutive numbers, consecutive even numbers or consecutive odd numbers is always the average of the middle two numbers.
When two groups of Parts or objects are combined together, then we can talk of the average of the entire group. However, if we know only the average of the two groups individually, we cannot find out the average of the combined group of objects.
Ex: The average of 6 consecutive even number is 21. Find the largest number? Largest no. = A + (n−1)
A = average
n = no. of terms
Largest no. = 21 + ( 6 -1) = 26
Ex: The average of 5 consecutive even number is 46. Find the smallest number? Smallest no. = A – (n – 1)
A = average
n = no. of terms
Smallest no. = 46 -( 5 -1)
= 42
Ex: The average of 6 consecutive odd number is 22. Find the smallest number?Smallest no. = A – (n – 1)
A = average
n = no. of terms
Smallest no. = 22 – ( 6 – 1)
= 17
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