Find the value of p, if mean of the following data is 18

Asked by arnima | 5th Mar, 2009, 10:33: AM

Expert Answer:

Finding the value of f.x for each value of x we get:

f.x  104     30     51    76   (20+p)5p      138

Now, mean  = Σ f.x / Σf

Σ f. x = 104+30+51+76+(20+p)5p+138 = 399+100p+5p2

Σf = 23+5p

mean = 18 (given)

Hence, 18 = 399+100p+5p2 / 23+5p

Solving this, we get the quadratic equation

p2+2p-3 = 0

this gives the values of p as -3 and 1.

Answered by  | 5th Mar, 2009, 12:01: PM

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