5+ 2(3 + 2x) = x + 3(x + 1)
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Answer:
The probability that "0" appears at most once in a telephone number is 0.82
Step-by-step explanation:
Telephone number = 10 digits
First digit = (1,2......9)------> there are 9 possible digits
digit 2 - digit 10 = (0,1,2......9) -----> there are 10 possible digits
Let's find the total amount of telefone numbers with those characteristics:
possible first digit X possible second digit X...............X possible tenth digit
9X10X10X10X10X10X10X10X10X10 =
Let's find the amount of telephone numbers that "0" appears at most once (it means 0 will occur either once or will not occur):
If "0" appears once, the rest of the numbers should be 1.2.....9 (9 possible digits)
9X10X9X9X9X9X9X9X9X9 =
If "0" doesn't appear, the ten digits should be 1,2....9
9X9X9X9X9X9X9X9X9X9 =
Finally, find the probability
P=(favorable outcomes/total outcomes)
P= = 0.82