Question 1200243
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A jar contains 6 red marbles numbered 1 to 6 and 4 blue marbles numbered 1 to 4. 
A marble is drawn at random from the jar. Find the probability that the marble is blue or odd-numbered.
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<pre>
    P(blue or odd-numbered) = P(blue) + P(odd-numbered) - P(blue AND odd-numbered) = 

                            = {{{4/10}}} + {{{(3+2)/10}}} - {{{2/10}}} = {{{7/10}}}.


Or mental reasoning says that there is 7 favorable marbles { 4 blue + disjoint 3 red odd-numbered }
of the total 6+4 = 10 marbles.
</pre>

Solved in two different ways.