Question

Из трехзначных чисел наугад выбирают одно число какова вероятность что не содержит цифру 3 при условием что оно нечетная

Answer 1

Всего трехзначных 999-99=900 чисел 
первой цифрой может быть любая из набора 1,2,4,5,6,7,8,9 -всего 8 допустимых цифр, второй - 9 допустимых (все кроме 3), третьей может быть 1 5 7 9 - 4 цифры. всего 8*9*4 чисел из 900 возможных
по определению вероятности Р=8*9*4/900=0,32

Answer 2

Probability of Selecting a Three-Digit Number Without the Digit 3, Given That It Is Odd

When selecting a three-digit number at random, the probability of choosing a number that does not contain the digit 3 and is odd can be calculated as follows:

1. Total Possible Three-Digit Numbers: There are 900 three-digit numbers in total (ranging from 100 to 999). 2. Total Possible Odd Three-Digit Numbers: Half of the three-digit numbers are odd, so there are 450 odd three-digit numbers. 3. Total Possible Odd Three-Digit Numbers Without the Digit 3: To find the number of odd three-digit numbers that do not contain the digit 3, we need to consider the possible combinations for each digit place (hundreds, tens, and units).

- For the hundreds place: There are 9 possible digits (1, 2, 4, 5, 6, 7, 8, 9) since 0 cannot be in the hundreds place. - For the tens and units places: There are 10 possible digits (0-9) for each place, excluding 3.

Therefore, the total number of odd three-digit numbers without the digit 3 is 9 * 10 * 10 = 900.

4. Calculating the Probability: The probability of selecting an odd three-digit number without the digit 3 is the ratio of the number of favorable outcomes to the total number of possible outcomes.

Probability = (Number of odd three-digit numbers without the digit 3) / (Total number of odd three-digit numbers)

Probability = 900 / 450 = 2

Therefore, the probability of selecting a three-digit number at random that does not contain the digit 3 and is odd is 2.