Question

1. A number is chosen from 1 to 20. Find the probability that the number chosen is : 
(i) a prime number (ii) a composite number 
(iii) a square number (iv) an odd number 
(v) an even number (vi) number between 7 and 14

Answer 1

Prime number - 2,3,5,7,11,13,17,19
Composite number - 4,6,8,9,10,12,14,15,16,18,20
Square number - 4,9,16
Odd number - 3,5,7,9,11,13,15,17,19
Even number - 2,4,6,8,10,12,14,16,18
Number between 7 to 14 - 8,9,10,11,12,13

Answer 2

Answer:

(1) A PRIME NUMBER :-

TOTAL NUMBER OF NUMBERS = 20

TOTAL NUMBERS OF PRIME NUMBER = 2,3,5,7,11,13,17,19==> 8

TOTAL PROBABILITY OF PRIME NUMBER ==> 8/20 ==> 2/5

(2)  A COMPOSITE NUMBER :-

TOTAL NUMBER OF NUMBERS = 20

TOTAL NUMBER OF COMPOSITE NUMBER = 4,6,8,9,10,12,14,15,16,18,20 ==> 11

TOTAL PROBABILITY OF COMPOSITE NUMBER ==> 11/20

(3) A SQUARE NUMBER

TOTAL NUMBER OF NUMBERS = 20

TOTAL NO. OF PERFECT SQUARE = 1,4,9,16==> 4

TOTAL PROBABILITY OF  SQAURE NUMBER ==> 4/20 ==> 1/5

(4) AN ODD NUMBER

TOTAL NUMBER OF NUMBERS = 20

TOTAL NUMBER OF ODD NUMBERS = 1,3,5,7,9,11,13,15,17,19==>10

TOTAL PROBABILITY OF ODD NUMBER ==> 10/20 ==> 1/2

(5) TOTAL NUMBER OF NUMBERS = 20

TOTAL NO. OF EVEN NUMBER ==> 2,4,6,8,10,12,14,16,18,20==>10

TOTAL PROBABILITY OF EVEN NUMBER ==> 10/20 ==>1/2

(6) TOTAL NUMBER OF NUMBERS = 20

 TOTAL NUMBER B/W 7 AND 14 ==> 7

TOTAL  PROBABILITY B/W 7 AND 14 ==> 7/20