Question

If the mean of the first n natural number is 15,
then find n.​

Answer 1

Answer:

N=29

Step-by-step explanation

first n natural numbers are 1,2,3,4,5,6.............n

mean =[1+2+3.......+n]/n

mean=[n/2[n+1]]/ n

[The sum of the first n natural numbers : Sn = n/2 (a + l ) = n/2(1 + n) = n/2(n +1)]

15  = (n + 1) /2  

15 × 2 = n + 1

30 = n + 1

n = 30 - 1

n = 29

Hence, the value of n is 29

Answer 2

Answer:

FIND MEAN OF FIRST N NATURAL NUMBERS

FIRST N NATURAL NUMBERS ARE 1,2,3......N

MEAN=SUM OF OBSERVATION/TOTAL OBSERVATIONS

MEAN=(1+2+3+...... N) /2

MEAN=(N/2(N+1)) /N

BY USING SUM OF FIRST N NATURAL NUMBERS FORMULA

SN=N/2(A+1) =N/2(1+N) =N/2(N+1)

15=(N+1) /2

15×2=N+1

N+1=30

N=30-1

N=29

THEREFORE THE VALUE OF N IS 29