there are 5 pennies. 7 nickels. 9 dimes.
two coins are selected and they must be the same type. there's no replacement
what's the probability?
two coins are selected and they must be the same type. there's no replacement
what's the probability?
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21 coins in total
Pr = (5 * 4 + 7 * 6 + 9 * 8) / (21*20) = 134 / 420 = 67/210 or 31.9% <------
..... pennies nickels dimes
Pr = (5 * 4 + 7 * 6 + 9 * 8) / (21*20) = 134 / 420 = 67/210 or 31.9% <------
..... pennies nickels dimes