Introduction to Probability

From a well shuffled pack of $52$ cards one card is drawn at random, The probability of getting a number card is

Find the probability that Ahaan scores $35$ marks in a $50$-mark test.

Suggest some events that could have the following probabilities.

$$\begin{gathered} i) \frac{1}{10} \\ ii) 50\% \\ iii) 100\% \end{gathered}$$

A box contains $40$ envelopes of which $25$ are ordinary (not meant for air mail) and $16$ are unstamped, while the number of unstamped ordinary envelopes is $10$. What is the probability that an envelope chosen from the box is a stamped air-mail envelope.

How to find probability?

What is Probability ? Give an example

A coin is tossed twice. Find the probability of getting both tails.

Find the probability of getting exactly one head when two coins are tossed simultaneously.

What is the probability of getting at least one head when two coins are tossed simultaneously?

Some events are easier to predict than others, but there are various chance expressions to describe the likelihood of something occurring.

Write these chance expression in the table.

• Very unlikely               
• Certain
• Somewhat unlikely
• Most likely
• Quite unlikely             
• Even chance
• Somewhat likely
• Most unlikely
• Very likely           
• Quite likely
• Impossible

Which of these does not describe an even chance of something happening?

Draw six equal squares on a piece of paper. Write the word SCHOOL with one letter per square.

$\boxed{\mathrm{S}} \boxed{\mathrm{C}} \boxed{\mathrm{H}} \boxed{\mathrm{O}} \boxed{\mathrm{O}} \boxed{\mathrm{L}}$

If you have all the letters face down and pick up two, you might choose both letter Os. What are the $10$ possible letter combinations that you might pick up?

Draw six equal squares on a piece of paper. Write the word SCHOOL with one letter per square.

$\boxed{\mathrm{S}} \boxed{\mathrm{C}} \boxed{\mathrm{H}} \boxed{\mathrm{O}} \boxed{\mathrm{O}} \boxed{\mathrm{L}}$

Remove the two letter Os and leave the others face down. Which pair describes the chance of choosing a letter S without looking?

Draw six equal squares on a piece of paper. Write the word SCHOOL with one letter per square.

$\boxed{\mathrm{S}} \boxed{\mathrm{C}} \boxed{\mathrm{H}} \boxed{\mathrm{O}} \boxed{\mathrm{O}} \boxed{\mathrm{L}}$

Cut out the squares. Turn them over and move the squares around. What is the chance of picking up the letter S without looking?

In a box, there are $8$ red, $7$ blue and $6$ green balls. One ball is picked up randomly. The probability that the ball is neither blue nor green is:

Two dice are thrown at the same time. The probability that, the sum of two numbers appearing on the top of the dice is greater than $6$ but less than $9$ is 

An octahedral die whose faces are numbered $1$ through $8$ (only one number on one face) is thrown three times. What is the probability that the product of the numbers obtained in first two throws is equal to the number obtained in the third throw?

A bag contains $5$ white balls and some black balls. If the probability of drawing a black ball is double that of a white ball, determine the number of black balls in the bag.

Two customers Shubham and Mayank are visiting a particular shop in the same week (Tuesday to Saturday). Each is equally likely to visit the shop on any day as on another day. Then the probability that both will visit the shop on different days?

Two customers Shubham and Mayank are visiting a particular shop in the same week (Tuesday to Saturday). Each is equally likely to visit the shop on any day as on another day. Then the probability that both will visit the shop on consecutive days is $\frac{8}{25}$.