Chapter No 11: Probability concepts

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Probability concepts

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A Simple Overview

Probability is a way of quantifying how likely an event is to occur. It ranges from 0, meaning the event is impossible, to 1, meaning the event is certain. For example, when you flip a coin, there is an equal chance of landing on heads or tails. This likelihood, or probability, helps us make sense of situations where outcomes are uncertain, from games to business decisions.

1. Basics of Probability

Probability provides a structured way to predict outcomes by counting possible results. For example, if you roll a six-sided die, there are six possible results. The chance of rolling a specific number, like 3, depends on these six possibilities. If all outcomes are equally likely, we can say each has the same chance.

2. Types of Events in Probability

In probability, events are defined by their nature and relationship with other events. Here are a few common types:

Independent Events: These are events where one does not affect the other. For example, if you roll two dice, the result of the first die does not change the outcome of the second.

Dependent Events: These events influence each other. For instance, if you draw a card from a deck, do not put it back, and then draw another card, the second draw depends on the first since there is one less card in the deck.

Mutually Exclusive Events: These events cannot happen at the same time. When rolling a single die, you cannot get both a 3 and a 5 in the same roll, making these outcomes mutually exclusive.

Complementary Events: This refers to outcomes where one event happening means the other cannot. For example, in a coin toss, getting heads and not getting heads are complementary events—if you get heads, you cannot also get tails.

3. Key Probability Concepts

Several important ideas help us think about probability more deeply:

Adding Probabilities: When considering the chance of one of several mutually exclusive events occurring, you can combine their chances. For example, if you want to know the likelihood of rolling either a 2 or a 5 on a die, you combine the chances of each outcome happening separately.

Multiplying Probabilities: If you want to know the chance of two independent events happening together, like flipping two coins and both landing on heads, you combine their individual chances. This approach applies only when one event does not affect the other.

Conditional Probability: This concept focuses on how the likelihood of an event changes if we know something else has happened. For instance, if you know a card drawn from a deck is red, it narrows down what other characteristics the card might have, changing the chance of drawing a heart versus a diamond.

4. Applications of Probability

Probability is a powerful tool that is widely used across different fields:

In Business and Finance: Probability models help companies make decisions with uncertain outcomes, like estimating future sales, assessing investment risks, or determining insurance premiums.

In Healthcare: Probability assists in understanding the chances of disease spread, treatment effectiveness, and the impact of public health decisions. It helps doctors and scientists make informed decisions about treatments and preventive measures.

In Gaming and Sports: Probability is fundamental to games of chance and sports betting. It helps determine fair odds and lets players assess the risk and potential reward of different outcomes.

In Everyday Life: Probability is used in daily life decisions, like checking the weather forecast to determine the likelihood of rain or using traffic data to estimate the time needed for a commute.

5. Common Misconceptions About Probability

People often have misunderstandings about probability, which can lead to errors in reasoning:

"Expected Results": People sometimes think probability guarantees specific outcomes. For example, even if you have a 50% chance of winning a game, you may not win exactly half the time in a small number of tries.

"Gambler’s Fallacy": This is the mistaken belief that past events can influence future independent events. For instance, if a coin lands on heads several times in a row, people may think tails is "due," but each coin flip is independent.

"Probability as Certainty": A high probability does not mean an outcome will definitely happen. Even with strong odds, unexpected results can still occur, and low-probability events can happen against the odds.

6. Conclusion

Probability concepts allow us to make better-informed predictions and decisions in uncertain situations. From science and finance to sports and everyday scenarios, probability gives us tools to understand possible outcomes and plan accordingly. By mastering these concepts, we improve our ability to think critically about uncertainty and make better choices in complex situations

1 / 25

The value of 0! is equal to _____ and 1! is equal to _____.

2 / 25

There are 30 students in PRC class consisting of 18 boys and 12 girls. 2 boys and 2 girls
are selected at random from this class, you are required to find how many different
combinations are formed?

3 / 25

If there are 5 Civic cars & 8 city cars. If two cars are selected, what is the probability that
both are Civics?

4 / 25

A coin is rolled three times, find the probability that exactly one head will appear

 

5 / 25

A wallet contains 65 notes of Rs 1,000 and 35 notes of Rs. 500 Four notes are selected at
random with replacement. Find the probability that sum of notes are Rs. 3,000

6 / 25

How many 3-digit numbers can be formed from the digits 1, 3, 4, 5, 7 and 9, which are
divisible by 2 and none of the digits is repeated?

7 / 25

If a consignment of 25 auto batteries 3 are defective. If a random sample of 5 batteries is
selected the probability of having exactly 2 defective batteries is:

8 / 25

A 4-digit pin code can begin with any number except 0 ,1,2. If repetition of the same digit
is allowed the probability that the pin will begin with 3 is?

9 / 25

The events A and B are mutually exclusive if P(A)=0.5 and P(B)=0.4 then P (A or B) is:

10 / 25

In how many different ways can the letters of the word 'LEADING’ be arranged in such a
way that the vowels always come together?

11 / 25

n how many different ways can the letter of the word “BINOMIAL” be arranged in such
a way that the vowels always come together?

12 / 25

While checking out and from a departmental store, a customer passes through one out of
the 12 cash counters C1 to C12 with equal probability. After that his bill is verified by one of
the 3 verifying officers V1, V2 or V3 with equal probability and then he embarks on one of
the two elevators E1 or E2 and is twice as likely to embark on E2 as it is twice as large as E1.
What is the probability that a consumer will pass through C1, verified by either V1 or V3 and embark
on E2

13 / 25

In a consignment of 25 auto-batteries, 3 are defective. If a random sample of 5 batteries is
selected, then probability of having exactly 2 defective batteries in the sample is:

14 / 25

Three dices rolled together. The probability of rolling a 3 on at least one of three dices is:

15 / 25

There are 5 red and 7 black cars for sale at fast wheels. If 2 cars are sold, what is the
probability that both are red?

16 / 25

In a bakery, 3 cakes of fresh cream pineapple, 4 cakes of chocolate, 2 cakes of
buttercream strawberry and 1 cake without cream are available. If two customers purchase
one cake each, such that first cake is replaced before the sale of the second then, the
probability that both the cakes would be of chocolate flavour is:

17 / 25

A wallet contains fifty Rs. 1,000 and fifty Rs. 500 currency notes. If four notes are drawn
from the wallet at random with replacement, the probability that the total amount drawn
would exactly be equal to Rs. 3,000 is:

18 / 25

A coin is tossed 3 times find the probability that it lands on head exactly once is?

19 / 25

If a coin is flipped three times, the possible sample will be:

20 / 25

Ali wishes to plant flowers in front of his house. His father has brought him a box
containing 3 tulips, 4 roses and 3 jasmines. If he selects five flowers at random, the
probability that 1 tulip, 2 roses and 2 jasmines are selected is:

21 / 25

A firm installed two machines U and V, on January 1, 2017. The probability that the
machines will break down during first year of operations is 0.2 and 0.1 for machines U and V
respectively. The probability that one of two machines will break down during the year is:

22 / 25

n how many different ways can the letters of the word “CORRECT” be arranged

23 / 25

There are 2 red balls, 2 green and 3 blue balls in a bag. It two balls are drawn at random.
What is the probability that none is blue?

24 / 25

In a certain town, 50% of the households own a cellular phone, 40% own a pager, and
20% own both a phone and pager. The proportion of households that own neither a cellular
phone nor a pager is_______.

25 / 25

A problem in statistics is given to three students A, B, C whose chances of solving are ½,
Âľ,1/4 respectively. What is the probability that problem will be solved?

Your score is

The average score is 55%

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