5 6 7 8 9 10 11 12 13 14 15 16 17 18
19 20 21 22 23 24 25
You have 21 numbers
Which of these numbers are divisible by 5 or 3
5,6,12,15,18,20,21,24,25
9/21 or a decimal if your teacher requires that format.
b) count up the even numbers and the prime numbers. Prime numbers are only divisible by 1 and itself.
Put this answer over 21.
c) all the numbers except 18. right? count them and divide by 21.
If a number is chosen at random from the integers 5 to 25 inclusive, find the probability that the number is
a) multiple of 5 or 3
b) even or prime numbers
c) less or greater than 18
3 answers
HOW DID YOU GET THE DIVISIBLE NUMBER BY 5 OR 3
Solution
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Total outcome= 21
a) p(multiple of 5 & 3)= 5/21+7/21= 5+7/21= 12/21= 4/7ans
b) p( Even or prime number)= 10/21+7/21= 10+7/21= 17/21ans
c) p(less or greater than 18)= 13/21+7/21= 13+7/21= 20/21ans
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Total outcome= 21
a) p(multiple of 5 & 3)= 5/21+7/21= 5+7/21= 12/21= 4/7ans
b) p( Even or prime number)= 10/21+7/21= 10+7/21= 17/21ans
c) p(less or greater than 18)= 13/21+7/21= 13+7/21= 20/21ans
5 answers