Thirty percent (30%) of carbon-14 will decay within how many years?

a. Sketch the graph, and shade the area of interest.

b. Find the value k such that P(x < k) = 0.30.

Short Answer

Expert verified

The graph, and shade of the interest area has been provided in step 1

the value of the probabilityP(x<k)=0.30is2,947.93

Step by step solution

01

Function of probability distribution 

It has been given that

X~Exp(0.000121)

So, the mean value m =0.000121

the formula of probability density is

At x= 0the value of f(x)lies in Y axis then value of

f(x)=0.000121e-0.000121×0=0.000121

that is equal to mean value of m.

The figure has been provided P(x<k)=0.30

02

  Formula of cumulative distribution 

P(X<x)=1-emx

m = 0.000121

Now to calculate 30 percentile, the equation is

P(x<k)=1-e0.000121k0.30=1-e0.000121ke0.000121k=0.70

Applying logarithm in both sides

ln(e0.000121k)=ln(0.70)k=0.35670.000121=2947.93

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