One hundred cards are numbered from 1 to 100. What will be the probability that a randomly chosen card has a digit 5?
To find the probability of randomly choosing a card with a digit 5, we need to determine how many cards have the digit 5 and divide that by the total number of cards.
Step 1: Determine the number of cards with the digit 5.
- We can find this by counting the numbers from 1 to 100 that contain the digit 5.
- The numbers that contain the digit 5 are: 5, 15, 25, 35, 45, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 65, 75, 85, 95 (19 numbers in total).
Step 2: Calculate the probability.
- Divide the number of cards with the digit 5 by the total number of cards.
- The total number of cards is 100.
- The number of cards with the digit 5 is 19.
- Divide 19 by 100: 19/100 = 0.19
Therefore, the probability of randomly choosing a card with a digit 5 is 0.19, or 19%.
To find the probability that a randomly chosen card has a digit 5, we need to determine how many cards have the digit 5 and divide that number by the total number of cards.
Step 1: Counting the cards with the digit 5:
- We know that the cards are numbered from 1 to 100.
- From 1 to 100, we have 10 cards numbered with a single digit 5: 5, 15, 25, ..., 95.
- Additionally, we have 10 cards numbered with double digits and the digit 5 in the tens place: 50, 51, ..., 59.
- Therefore, there are 10 single-digit cards and 10 double-digit cards with the digit 5, making a total of 20 cards with the digit 5.
Step 2: Finding the probability:
- The total number of cards is given as 100.
- Now we can determine the probability by dividing the number of cards with the digit 5 by the total number of cards: 20/100 = 0.2 or 20%.
Therefore, the probability that a randomly chosen card has a digit 5 is 0.2 or 20%.
all the numbers that don't have a 5 in them:
8 x 9 = 72 , (they can start with 1,2,3,4,6,7,8,9 and they can end with 0,1,2,3,4,6,7,8,9 )
Those with a 5 are 100-72 = 28
prob(have a 5) = 28/100 = 7/25