Question

A person observed the first 4 digits of your 6-digit PIN. What is the probability that the person can guess your PIN?

पर्याय

• `1/81`

• `1/100`

• `1/90`

• 1

Answer 1

`bb(1/100)`

Explanation:

Our 6-digit PIN would look like:

___  ___  ___  ___  ___  ___

Of which, the person knows the first 4 digits:

  X      X      X      X                  

Now, there is only 1 correct pin.

∴ Number of correct PIN = 1

  X      X      X      X                  

And, the person can put any digit from 0 to 9 in the last two positions.

So, there are 10 options for one position.

Now,

Total Number of ways of putting last 2 digits = 10 × 10 = 100

Thus,

Required Probability = `"Number of ways he can put correct PIN"/"Total Number of ways for putting last 2 digits"`

= `1/100`