Lesson Notes By Weeks and Term v4 - SHS 2
PROBABILITY/CHANCE
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PROBABILITY/CHANCE
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Subject: Mathematics
Class: SHS 2
Term: 2nd Term
Week: 19
Grade code: 2.4.2.LI.2
Strand code: 4
Sub-strand code: 2
Content standard code: 2.4.2.CS.1
Indicator code: 2.4.2.LI.2
Theme: MAKING SENSE OF AND USING DATA
Subtheme: PROBABILITY/CHANCE
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Probability is a branch of mathematics that helps us understand and quantify uncertainty. In our daily lives in Ghana, we are constantly faced with situations where the outcome is not certain. Will it rain today in Accra? Will the Black Stars win their next match? What are the chances of the traffic light at the Tetteh Quarshie Interchange being green when I get there? By understanding probability, we can move from simple guessing to making more informed decisions, whether in games like *Ludo*, in business, or in planning our daily activities. This lesson focuses on what happens when we consider the probability of two events happening one after the other.
A. What is Probability?
Probability is a measure of how likely an event is to happen. It is always a number between 0 and 1. A probability of 0 means the event is impossible. (e.g., The probability of the sun rising from the west). A probability of 1 means the event is certain. (e.g., The probability that you are in a mathematics class right now).
The basic formula for the probability of an event (E) is: $$ P(E) = \frac{\text{Number of Favourable Outcomes}}{\text{Total Number of Possible Outcomes}} $$
Example: What is the probability of rolling a '4' on a standard six-sided die? Favourable outcomes = {4} (There is only one '4') Total possible outcomes = {1, 2, 3, 4, 5, 6} (There are six faces) Therefore, $P(\text{rolling a 4}) = \frac{1}{6}$ B. Combined Events: Independent vs. Dependent Events