Explain. If it rains on Saturday, the probability of rain on Sunday is 60%. Can you now determine the probability of rain over the weekend?

Burhan Hopper

Burhan Hopper

Answered question

2021-09-21

The weather forecaster says that the probability of rain on Saturday is 20% and the probability of rain on Sunday is 30%. Can you determine the probability of rain over the weekend(Saturday or Sunday)? Explain
If it rains on Saturday, the probability of rain on Sunday is 60%. Can you now determine the probability of rain over the weekend?

Answer & Explanation

FieniChoonin

FieniChoonin

Skilled2021-09-22Added 102 answers

I hope my answer below will help you
fudzisako

fudzisako

Skilled2023-06-11Added 105 answers

Step 1. The weather forecaster says that the probability of rain on Saturday is 20% and the probability of rain on Sunday is 30%.
Let's denote the probability of rain on Saturday as P(S) and the probability of rain on Sunday as P(S), where S represents the complement (no rain) of event S (rain).
P(S)=0.20 and P(S)=0.30.
Step 2. We need to determine the probability of rain over the weekend (Saturday or Sunday).
To find the probability of rain over the weekend, we need to calculate the probability of rain on Saturday and/or Sunday. Since these events are mutually exclusive (it cannot rain on both days simultaneously), we can use the addition rule of probability.
P(SS)=P(S)+P(S) (where represents the union of events)
Therefore, the probability of rain over the weekend is P(SS)=0.20+0.30=0.50.
So, the probability of rain over the weekend is 50%.
Step 3. If it rains on Saturday, the probability of rain on Sunday is 60%.
Let's denote the event of rain on Sunday given rain on Saturday as P(S|S), where S represents rain on Sunday and S represents rain on Saturday.
P(S|S)=0.60.
Step 4. We need to determine the probability of rain over the weekend given rain on Saturday.
To find the probability of rain over the weekend given rain on Saturday, we can use the definition of conditional probability.
P(SS|S)=P((SS)S)P(S)
The numerator represents the intersection (overlap) of events rain over the weekend and rain on Saturday, while the denominator represents the probability of rain on Saturday.
Since rain on Saturday and rain over the weekend are the same event in this case (because if it rains on Saturday, it automatically rains over the weekend), we have:
P(SS|S)=P(S)P(S)=1
Therefore, the probability of rain over the weekend given rain on Saturday is 100%.
To summarize:
- The probability of rain over the weekend (Saturday or Sunday) is 50%.
- If it rains on Saturday, the probability of rain over the weekend is 100%.
xleb123

xleb123

Skilled2023-06-11Added 181 answers

Result:
- The probability of rain over the weekend without considering the additional information is 50% (P(W)=0.5).
- Considering the new information, if it rains on Saturday, the probability of rain over the weekend is 12% (P(W)=0.12).
Solution:
Let's denote the probability of rain on Saturday as P(S), the probability of rain on Sunday as P(S), and the probability of rain over the weekend as P(W).
According to the given information:
- The probability of rain on Saturday is 20%, which can be expressed as P(S)=0.2.
- The probability of rain on Sunday is 30%, which can be expressed as P(S)=0.3.
To determine the probability of rain over the weekend, we need to calculate P(W). Since rain can occur either on Saturday or Sunday, we can calculate the probability of rain over the weekend by taking the union of the events S and S.
Using the formula for the union of two events, we have:
P(W)=P(SS)
Now, since S and S are mutually exclusive events (rain cannot occur on both Saturday and Sunday), we can apply the addition rule of probability:
P(W)=P(S)+P(S)
Substituting the given probabilities, we get:
P(W)=0.2+0.3=0.5
Hence, the probability of rain over the weekend is 50%, or equivalently P(W)=0.5.
Now, let's consider the additional information:
''If it rains on Saturday, the probability of rain on Sunday is 60%.''
Let's denote this conditional probability as P(S|S), which represents the probability of rain on Sunday given that it rained on Saturday.
According to the given information, P(S|S)=0.6.
To determine the updated probability of rain over the weekend, denoted as P(W), we need to consider two scenarios:
1. If it doesn't rain on Saturday (complement of event S), then P(W)=P(W) remains unchanged at 0.5.
2. If it does rain on Saturday (event S), the probability of rain on Sunday is P(S|S)=0.6. Therefore, the updated probability of rain over the weekend is:
P(W)=P(SS)=P(S)·P(S|S)
Substituting the given values, we have:
P(W)=0.2·0.6=0.12
Hence, the updated probability of rain over the weekend, considering the new information, is 12%, or equivalently P(W)=0.12.
Andre BalkonE

Andre BalkonE

Skilled2023-06-11Added 110 answers

Given that the probability of rain on Saturday is 20%, we have P(S)=0.20.
The probability of no rain on Saturday is P(S)=1P(S)=10.20=0.80.
Similarly, given that the probability of rain on Sunday is 30%, we have P(S)=0.30.
The probability of no rain on Sunday is P(S)=1P(S)=10.30=0.70.
To determine the probability of rain over the weekend (Saturday or Sunday), we can use the addition rule of probability. This rule states that for two mutually exclusive events, the probability of either event occurring is the sum of their individual probabilities.
In this case, Saturday and Sunday are two mutually exclusive events since rain can only occur on one of the days. Therefore, we have:
P(SS)=P(S)+P(S)
P(SS)=0.20+0.30=0.50
Hence, the probability of rain over the weekend is 50% or 0.50.
Now, if it rains on Saturday, the probability of rain on Sunday is given as 60%. Let's denote this conditional probability as P(S|S).
Using this information, we can update our probability calculation for rain over the weekend, taking into account the condition that it rained on Saturday.
The probability of rain on Sunday given that it rained on Saturday is denoted as P(S|S)=0.60.
To determine the probability of rain over the weekend given that it rained on Saturday, we can use the multiplication rule of probability. This rule states that the probability of the intersection of two events is equal to the product of their individual probabilities.
In this case, we want to find P(SS|S), which represents the probability of rain over the weekend given that it rained on Saturday.
P(SS|S)=P(S)|S)+P(S|S)
P(SS|S)=0.60+1=1.60
However, a probability cannot exceed 1, so the probability of rain over the weekend given that it rained on Saturday remains 1 (or 100%).

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