solutions
Probability
Level
2
Find the number of positive integral solutions of xyzw=90 :
400
240
160
450
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
u can just divide the number into its prime factors : the prime factors of 90 are 2,3,5 2x3^2x5=90 now since there are four variables u can divide them as follows 2^(a+b+c+d) x 3^(e+f+g+h) x 5^(i+j+k+l)
now (a+b+c+d)=1; (e+f+g+h)=2; (i+j+k+l)=1;
apply the basic rules of combinations to get the answer:160