doing some probability questions for a assignment, I think i have them right but maths isnt my strong suit could anyone look at these two questions comment if these are correct

A computer randomly chooses 4 different letters from the 26 letters of the alphabet.26*26*26*26 =456976

Calculate the probability that the chosen letters spell the word ZONE

solution:

p(zone) is 1 over 456976

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Suppose A and B are events with P(A) = 0.4 and P(B) = 0.4.

Find the probability that

(i) A does not occur

(ii) B does not occur

(iii) A or B occurs

(iv) Neither A nor B occurs

Solution:

(i) P(not A)= 1-0.4 = 0.6 = 3 over 5

(ii) P(not B) = 1 - 0.4 = 0.6 = 3 over 5

(iii)P(AorB) = 0.4 +0.4 =0.8 = 4 over 5

(iv) P(not A or B) = 1 - 0.8 =0.2 = 1 over 5 (*sorry i dont know hoe to edit this to show fractions)

thanks in advance .