document.write( "Question 1182240: Every cereal box has a gift inside, but you cannot tell from the outside what the gift is.
\n" ); document.write( "The store manager assures you that 21 of the 42 boxes on the shelf have the secret decoder ring.
\n" ); document.write( "The other 21 boxes on the shelf have a different gift inside.
\n" ); document.write( "If you randomly select two boxes of cereal from the shelf to purchase, what is the probability that BOTH of them have the decoder ring?
\n" ); document.write( "_______
\n" ); document.write( "Round decimal to 4 places \n" ); document.write( "
Algebra.Com's Answer #812213 by mathmate(429)\"\" \"About 
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Given:
\n" ); document.write( "21 of 42 boxes have ring.
\n" ); document.write( "Once opened, cannot be replaced.
\n" ); document.write( "Find probability that two randomly selected boxes both have the ring.
\n" ); document.write( "
\n" ); document.write( "Solution:
\n" ); document.write( "probability that the first one is a ring
\n" ); document.write( "= 21 out of 42
\n" ); document.write( "= 21/42
\n" ); document.write( "= 1/2
\n" ); document.write( "probability that the second box is a ring
\n" ); document.write( "= 20 out of 41
\n" ); document.write( "= 20/41
\n" ); document.write( "
\n" ); document.write( "Probability that both of them are rings, we use the multiplication rule to get
\n" ); document.write( "P(R,R)
\n" ); document.write( "= (1/2) * 20/41
\n" ); document.write( "= 10/41
\n" ); document.write( "= 0.24390... (approximately)
\n" ); document.write( "= 0.2439 (to four decimal places) \n" ); document.write( "
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