Test

Yep......you're exactly correct !!!!!!

That handwriting.

yea :D

i found 0.58 answer

independent it is mean: Tom or John will pass the exam not both 

T-   3/10

J-    4/10 

the probability that they will pass is 3/10+4/10=7/10=0.7

the probability that they will both pass is 3/10x4/10=12/100=0.12

0,7-0.12=0.58 (D)

just a stupid question or my answer is wrong

Let's see, Solveit.....

P(A and B)  = P(A) * P(B)   [  if A, B  are independent events  ]

"At least one" means that we have three possibilities:

Let A  = probability that Tom passes= .3  and B = probability that  John passes = .4

Both pass  =  P (A and B)  = .3 * . 4  = .12

Tom passes, and John doesn't = P (A and not B) =.3 * .6  = .18

John passes and Tom doesn't  = P(not A and B)  = .7 * .4   = .28

Summing these, we have    .12 + .18 + .28  =  .58    (D)

but what i found then ? :(

my answer is correct but not the way 

Yeah......I see what you mean.....

Looking at your approach....you could  compute this as :

1  - [Probability that neither pass ]  =

1 - [ .7  *  .6]  =  1  - .42   = .58

Does that make sense ???

Thanks CPhill i understood everything !

No prob, Solveit.....!!!!