Definition
Theoretical Probability is the ratio of the number of favorable outcomes to the total possible outcomes of an event.
Expressing probability as a formula:
![\text{probability = }\frac{Number\text{ of favorable outcomes}}{Total\text{ possible outcomes of an event}}](https://img.qammunity.org/2023/formulas/mathematics/high-school/duriaahhiw09mr0f0l7bckwjxsk2h9b2v4.png)
Information about a standard deck of cards:
A standard deck of cards has four suits: hearts, clubs, spades, diamonds. Each suit has thirteen cards: ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, jack, queen, and king. Thus the entire deck has 52 cards total.
(a) Picture card (J, Q, and K)
In a standard deck, there are 4 Jacks, Queens, and Kings. Hence, the probability of J, Q, and K are:
![\begin{gathered} \text{Number of picture cards = 4 }*\text{ 3} \\ =\text{ 12} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/vomjvh2t8kfhet8wd6zh6dqifph21gplv3.png)
Probability as a fraction:
![=\text{ }(12)/(52)](https://img.qammunity.org/2023/formulas/mathematics/high-school/jikz157z4dbnl70dvq2biw3cg41pg666qh.png)
In decimal:
![=\text{ }0.23](https://img.qammunity.org/2023/formulas/mathematics/high-school/hfw6ep417bnqpd9gq29kxu9id7n3lniyjb.png)
Percent:
![\begin{gathered} =\text{ 0.23 }*\text{ 100} \\ =\text{ 23\%} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/l0xu7mjrkcwuz2fd036yu7svm37rvoo8ep.png)
(b) 9 or 10
There are 4 cards labeled 9 and 10 each.
Probability as a fraction:
![\begin{gathered} P(9or10)=\text{ P(9) + P(10)} \\ =\text{ }(4)/(52)\text{ + }(4)/(52) \\ =\text{ }(8)/(52) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/k956jif70un2a7axn8dncemb9vfkvtyrxl.png)
In decimal:
![=\text{ 0.15}](https://img.qammunity.org/2023/formulas/mathematics/high-school/v0uq7xhpe9kegm7z66qvuidtdp3tdl0ikb.png)
In percent:
![\begin{gathered} =\text{ 0.15 }*\text{ 100} \\ =\text{ 15\%} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/m3npi54kg39j6iko42bofnog032dqbedjt.png)
(c) 2 of heart
In a standard deck of cards, there are only one 2 of hearts.
Probability as a fraction:
![=\text{ }(1)/(52)](https://img.qammunity.org/2023/formulas/mathematics/high-school/l4m5690ak4us8v69yfhssbhgv678r7tto4.png)
In decimal:
![=\text{ 0.02}](https://img.qammunity.org/2023/formulas/mathematics/high-school/92om70qk9qq44blqy3y1py3190795id89k.png)
In percent:
![\begin{gathered} =\text{ 0.02 }*\text{ 100} \\ =\text{ 2\%} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/fai8d931zelsz1ghxh1l9za0aopw5cjor1.png)