00:01
Hi, in this question, given that suppose a fair coin is tossed 20 times, what is the probability of observing more than 15 heads? so here we know that the probability of getting head equals 1 by 2 and the probability of getting head is 1 by 2.
00:49
So, we can write the probability of getting head equals 1 by 2 is 1 by 2.
00:53
And here tossed 20 times, so n equals 10.
01:01
Here we have to find the probability.
01:05
So probability of x equals x equals by using the known formula ncx q power n minus x into p power x.
01:15
On substituting all the known values in this, here the probability of x greater than 15.
01:23
So which is equal to probability of x equals 16 plus probability of x equals 17 plus probability of x equals 18 plus probability of x equals 19 plus probability of x equals 20.
01:39
On substituting all the values in the above, then we get 20c16 0 .5 the whole power 20 minus 16 into 0 .5 the whole power 16 plus 20c17 0 .5 the whole power 20 minus 17 into 0 .5 the whole power 17.
02:01
By similar way on x equals 18, we get 20c18 0 .5 the whole power 20 minus 18 0 .5 the whole power 18 plus here 20c19 0 .5 the whole power 20 minus 19 into 0 .5 the whole power 19 plus here 20c20 0 .5 the whole power 20 minus 20 into 0 .5 the whole power 20.
02:32
On further simplified which is equal to 0 .0059.
02:41
Next move on to second question...