Two dice are thrown simultaneously. The probability that the sum is odd or less than $7$ or both is:

$A$ coin is tossed twice. If events $A$ and $B$ are defined as: $A = \text{head on first toss}$,$B = \text{head on second toss}$. Then the probability of $A \cup B = $

For two given events $A$ and $B$,$P(A \cap B)$ is:

There are three events $A, B, C$,one of which must and only one can happen. The odds are $8:3$ against $A$,$5:2$ against $B$,and the odds against $C$ are $43:17k$. Then the value of $k$ is:

Fill in the blank in the following table:

$P(A)$	$P(B)$	$P(A \cap B)$	$P(A \cup B)$
$0.35$	$..........$	$0.25$	$0.6$

If the probabilities of a student passing in the first,second,or third grade are $1/10$,$3/5$,and $1/4$ respectively,then the probability of the student failing (getting a fourth grade) is ........