anon1 wrote:

The chance of rain on any given day in Tel-Aviv is 50%. What is the probability that it rained in Tel-Aviv on exactly 4 out of 6 randomly chosen days?

A. 15/64

B. 30/64

C. 1/2

D. 1/4

E. 52/64

Din any body realised, we can also solve it without probability?

Critical Thinking Method: Total event occurrence possibility:

(0 rainy day / 6 Days ; 1 rainy day / 6 Days ; 2 rainy day / 6 Days ; 3 rainy day / 6 Days ; 4 rainy day / 6 Days ; 5 rainy day / 6 Days ; 6 rainy day / 6 Days ; )

So as per question the probability for 3 rainy day / 6 Days = 50%

Considering this as an universal occurrence; rest possibilities have a probability of 50% in together. So any option will have possibility of at-least <50% chance.

This helps you to get rid of options: B, E & C.

Now, on an average with 6 event occurrence and 50% chances for all you have even chances of 7% for all the events. Now if we even consider 3 events with 0% probability, we have a max of 21% chance which fits our question statement and options A

PS: Folks let me know if the critical thinking approach was OK. As i know it was fast for sure :P