Question

a spinner is marked with numbers from 1 to 20 . find the probability of getting. (a) a prime number (b) a multiple of 3

Answer 1

prime numbers from 1 to 20 are 3)2,3,5,7,11,13,17,19

So total prime no's are 8

a) probability = 8/20 = 2/5

b) multiple of 3 are 3,6,9,12,15,18

So total 6

so probability = 6/20 = 3/10

Answer 2

TOTAL NUMBER MARKING ON SPINNER = 20

PRIME NUMBER BETWEEN 1 TO 20

2. 3. 5 . 7. 11. 13. 17. 19

SO PRIME NUMBER BETWEEN 1 TO 20 = 8

PROBABILITY TO GETTING PRIME NUMBER

$= \frac{pime \: \: number}{total \: number \: \: }$

$= \frac{8}{20}$

$= \frac{2}{5}$

2ND ANS

MULTIPLE OF 3

3. 6 .9. 12. 15 .18

NUMBER MULTIPLE OF 3 =6

PROBABLITY TO GETTING MULTIPLE OF 3

$= \frac{number \: multiple \: of \: 3}{total \: number \: }$

$= \frac{6}{20}$

$= \frac{3}{10}$