Question

the probability of guessing the correct answer to certain question is x/5. if the probability of not guessing a correct answer is 2x/3 . find the value of x.

Answer 1

Let P(E) is guessing the correct answer & P(not E) is not guessing the correct answer

P(E)= x/5 (given)
P(not event)=2x/3 (given)
P(E)+P(not E)= 1
x/5+2x/3=1
3x/15+10x/15=1
(3x+10x)/15=1
13x/15=1
13x=1×15
x=15/13

Answer 2

Hi there !

Probability  of guessing the correct answer = x/5

Probability of not guessing a correct answer = 2x /3

Probability sum = 1

x/5 + 2x/3 = 1

lcm [ 5 , 3 ] = 15

3x/15 + 10x/15 = 1

13x/15 = 1

13x = 15

x = 15/13