antlad

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SerJibblenuts:
The Probability that Azher, who always walks to work, arrives late on any day is 0.11. Calculate the Probability that, during a period of 20 working days, he is late on exacalty 4 days.

SHOW WORKING

using the binomial theory : p(x)=nCx (p)^x (q)^n-x

let the probability of arriving late be P = 0.11

let the probability of not arriving late be q = 1-0.11= 0.89

n=20, x=4

workings
p(x=4) = 20C4 * (0.11)^4 * (0.89)^16
=4845 * (0.0001464) * (0.1549)
p(x=4)=0.11
conclusion : the probability that he comes late in exactly 4 days is 0.1 i.e 1 in every 10 chances

antladDec 4, 2013