probability

Let A = \left\{1,2,3 ... 10 \right\} and B = \left\{1,2,3 ... 20 \right\} A function is chosen randomly from A to B,what is the probability that it is non decreasing?

9 Answers

106
Asish Mahapatra ·

total no. of functions is 2010
now, for function to be non decreasing.... we have either the function is constant or increasing

No. of functions where the function is continuously decreasing is:
20!/10! as order is to remain same (i.e. decreasing)

So, prob of continously decreasing function is 20!/10!.2010

so, desired prob is 1-20!/10!.2010 i.e. 1-20P10/2010

1
Vivek ·

can u explain

"No. of functions where the function is continuously decreasing is:
20!/10! as order is to remain same (i.e. decreasing)"

106
Asish Mahapatra ·

is the answer correct btw.??
oh i din see ur doubt it will take some time for me to think and explain... pls wait....anyway is the ans correct? theres no point in explaining the wrong answer as u(and I) will get even more confused

1
Vivek ·

oh,let me check

the ans is 29C10/2010

106
Asish Mahapatra ·

then i dont know..... how 29C10 .. ??[7]

62
Lokesh Verma ·

Let the values of f(i) be denoted by ni

we know the

n1= n0+k1
n2= n1+k2
n3= n2+k3

n10= n9+k10 <=20

take summation,

n10= n0+k1+k2+k3+....k10 <=20

we kknow that n0>=1

so we can replace this with 1+k0
thus,

k0+k1+k2+k3+....k10 <=19

thi sis done in 29C10 ways

total no of ways is 2010

hence the answer :)

13
Двҥїяuρ now in medical c ·

wow...nice one.....!!

24
eureka123 ·

Sorry sir but I cant understand the solution....can you xplain it again plzzzzzz in a diff manner......[1]

1
Vivek ·

thanks bhaiyya,gr8 soln!!

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