need some help

#1
Hello,
I need some help with this task:
The price at which buyers are willing to pay for a book subdivided by chi square
distribution with an unknown parameter k. 18 out of 118 customers bought book For £ 20. And I need to evaluate the unknown distribution parameter k.

I would appreciate any ideas. Thanks.

(ps. sorry for mistakes I'm not a native English speaker :) )
 
#3
X~chisq(k) <- as far as I understand I need to evaluate parameter "k"
I also have this example on same task with Pareto distribution:

N<-118
n<-18
P<-(N-n)/N
P
#when t=1
X1<-ppareto(20,1,2)
X1
#when t=2
X2<-ppareto(20,2,2)
X2
#when t=5
X3<-ppareto(20,5,2)
X3
#when t=10
X4<-ppareto(20,10,2)
X4
#X4~P, so I'll use t=10.
A<-rpareto(131,10,2)
A


I think I need to do something similar but I dont know how to make this work with chi-square.