Question

Find P(not a 1).

X 1 2 3 4
P(X) 0.30 0.40 0.15 0.15

Answer 1

Ans = 1 - P( it is a 1)
        = 1 - 0.30
        =  0.70

Answer 2

Answer: $\text{P(not 1)}=0.70$

Step-by-step explanation:

The given table :

X         1     2     3     4

P(X)    0.30 0.40  0.15 0.15

From the above table we can see that $\text{P(1)}=0.30$

Also we know that the probability of complement of any event A is given by :-

$\text{P(not A)}=1-P(A)$

Therefore,  

$\text{P(not 1)}=1-\text{P(1)}\\\\\Rightarrow\ \text{P(not 1)}=1-0.30\\\\\Rightarrow\ \text{P(not 1)}=0.70$