kutkut wrote:What is the probability that, twelve seconds from a randomly selected starting time, a certain digital clock will display a number of seconds x such that x < 10 ?
(A) 19/60
(B) 3/10
(C) 1/5
(D) 11/60
(E) 1/6
The key thing to realize is that:
The probabilty that 0 seconds from a starting time, the clock will display a number of seconds x such that x < 10
is equal to,
The probabilty that 5 seconds from a starting time, the clock will display a number of seconds x such that x < 10
is equal to,
The probabilty that 10 seconds from a starting time, the clock will display a number of seconds x such that x < 10
Therefore we eliminate the phrase "twelve seconds from a randomly selected starting time"
The re-phrased qustion is:
What is the probability that a clock will display a number of seconds x such that x < 10 ?
x<10 means x could be 0 to 9 which are 10 choices
We know the total number of seconds the clock can display is 60 [0sec - 59sec]
therefore probability = 10/60 = 1/6
ans =
e
