Prime number

Jan wrote any number from 1 to 20. What is the probability that he wrote the prime number?

Correct answer:

p =  0.4

Step-by-step explanation:

$$\begin{gathered} p:2;3;5;7;11;13;17;19 \\ p={\displaystyle \frac{8}{20}}={\displaystyle \frac{2}{5}}=0.4 \end{gathered}$$

Try another example

Related math problems and questions:

• Raffle
  In the pool is numbers from 1 to 115. What is the probability that a randomly selected number is not a prime number?
• Balls
  From the bag with numbered balls (numbers 1,2,3,. ..20) we pick one ball. What is the probability of choosing a number containing 1?
• 9.A
  9.A to attend more than 20 students but fewer than 40 students. A third of the pupils wrote a math test to mark 1, the sixth to mark 2, the ninth to mark 3. No one gets mark 4. How many students of class 9.A wrote a test to mark 5?
• Drawing from a hat
  When drawing numbers from a hat from 1 to 35, we select random given numbers. What is the probability that the drawn numbers will be divisible by 8 and 2?
• Air draft
  The numbers 1,2,3,4,5 are written on five tickets on the table. Air draft randomly shuffled the tickets and composed a 5-digit number from them. What is the probability that he passed: and, the largest possible number b, the smallest possible number c, a
• Three dice
  What is the probability that when we roll three dice, we roll the numbers 1,2,3?
• Probability - tickets
  What is the probability when you have 25 tickets in 5000 that you not wins the first (one) prize?
• Probability
  How probable is a randomly selected three-digit number divisible by five or seven?
• Dices
  We will throw two dice. What is the probability that the ratio between numbers on first and second dice will be 1:2?
• Event probability
  The probability of event P in 8 independent experiments is 0.33. What is the probability that the event P occurs in one experiment (chance is the same)?
• Rectangle
  In a rectangle with sides, 8 and 9 mark the diagonal. What is the probability that a randomly selected point within the rectangle is closer to the diagonal than to any side of the rectangle?
• Five-digit number
  Anna thinks of a five-digit number that is not divisible by three or four. If he increments each digit by one, it gets a five-digit number that is divisible by three. If he reduces each digit by one, he gets a five-digit number divisible by four. If it sw
• Z9-I-4
  Kate thought a five-digit integer. She wrote the sum of this number and its half at the first line to the workbook. On the second line wrote a total of this number and its one fifth. On the third row, she wrote a sum of this number and its one nines. Fina
• Pediatrician
  Pediatrician this month of 20 working days takes 8 days holidays. What is the probability that on Monday it will be at work?
• Peaches
  There are 20 peaches in the pocket. 3 peaches are rotten. What is the probability that one of the randomly picked two peaches will be just one rotten?
• Basketball
  Peter and Franta threw to the basket. Each had 20 attempts. Peter scored thirteen and twelve Franta. Give them percentage success.
• We roll
  We roll two dice A. - what is the probability that the sum of the falling numbers is at most 4 B. - is at least 10 C. - is divisible by 5?