PROBABILITY WORD PROBLEMS WORKSHEET

Problem 1 :

The record of a weather station shows that out of the past 150 consecutive days, its weather forecasts were correct 110 times.

i) What is the probability that it was correct on a given day ?

ii) What is the probability that it was not correct on a given day ?

Solution

Problem 2 :

The percentage of marks obtained by a student in the monthly unit tests are given below :

Based on this data, find the probability that the students gets more than 75% marks in a unit test.

Solution

Problem 3 :

A company selected 4000 households at random and surveyed them to find out a relationship between income level and the number of television sets in a home. The information so obtained is listed in the following table :

i) Of a household earning $10000 – $14999 per year and having exactly one television.

ii) Of a household earning $25000 more per year and owning two television.

iii) Of a household not having any television.

Solution

Problem 4 :

Two dice are thrown simultaneously 500 times. Each time the sum of the two numbers appearing on their tops is noted and recorded as given in the following table :

If the dice are thrown once more, what is the probability of getting the sum :

i) 3 ?

ii) More than 10 ?

iii) Less than or equal to 5 ?

iv) Between 8 and 12 ?

Solution

Problem 5 :

Over the past 200 working days, the number of defective parts produced by a machine is given in the following table :

Determine the probability that tomorrow’s output will have :

i) No defective part.

ii) At least one defective part.

iii) Not more than 5 defective parts.

iv) More than 13 defective parts.

Solution

Problem 6 :

A school management committee interviewed some people for the post of principle. The committee wanted that the female candidate should also be given the fair chance. So, they called the male & female candidates 2 : 3 ratio.

i) What is the probability that female candidate being selected ?

Solution

Problem 7 :

100 cards marked from 2 to 101 are placed in a box & mixed thoroughly. One card is drawn at random from the box. Find the probability that number on the card is :

i) An even number.

ii) A number, which is a perfect square ?

iii) A prime number less than 20.

Solution

Problem 8 :

A survey was conducted in a group of students as a part of their environment awareness program in which they collected the following data regarding the number of plants planted in 30 hours in a locality

i) Find the probability of the number of hours having 12 – 15 plants.

ii) Find the probability of number of hours having less than 6 plants.

Solution