The answer to your question is 11 world championships
Answer:

Step-by-step explanation:
Answer:
Therefore the required probability is 
Step-by-step explanation:
The probability of success is 
The number of trial = 4
X= the items survive out of 4
p =the probability of success and q = the probability failure.
p=
and 



Therefore the required probability is 
Given -:
EF = 2X-7
FG = 4X-20
EG = 21
FIND OUT
EF =?
FG = ?
To proof
as given in the question
we have the value of EF = 2X-7 , FG = 4X-20 and EG = 21
Thus we have
EG = EF + FG
21 = 2X-7 + 4X- 20
21 = 6x - 27
48 = 6x
x = 8
Hence proved
Now put this value

Now

Hence proved