Question

If you roll a 10-slided dice 3 times, what is the probability that they form neither a strictly increasing nor a strictly decreasing series?

Answer 1

Answer:

0.76

Explanation:

Answer 2

Answer:

0.76

Explanation:

Let the number of strictly increasing arrangements  be = X

Let the number of strictly decreasing arrangements  be = Y

Let the number of neither the strictly decreasing nor strictly increasing  be = Z

Thus ,

X+Y+Z=1000

A strictly increasing arrangement from the opposite side, will look like a strictly decreasing arrangement.

Thus, X=Y

= 2X+Z=1000

For an increasing arrangement ,all the three numbers should be different which can be done in 10C3 ways.

Z = 1000- 10C3 × 2

= 760

Thus, the probability

= 760/1000

= 0.76