Pricing
19/3338–12FE Reference Handbook 10.4 · Probability and Statistics
1. Quadratic Formula2. Law of Cosines3. Standard Normal z-Score4. Law of Sines5. Power Rule6. Definite Integral of a Power7. Dot (Scalar) Product8. Cross Product Magnitude9. Sample Standard Deviation10. Binomial Probability11. z Confidence Interval for the Mean12. Circle: Area, Circumference, Arc13. First-Order Linear DE14. Trapezoidal Rule15. Linear Least Squares16. Poisson Probability Mass Function17. Newton–Raphson Iteration18. 2×2 Determinant and Inverse19. Combinations C(n,k)20. Linear Interpolation21. Second-Order Linear DE (Constant Coeff.)22. Exponential Growth and Decay

Handbook formula

Combinations C(n,k)

Unordered selections. Binomial probabilities use C(n,k) p^k (1−p)^{n−k}. Permutations P(n,k)=n!/(n−k)! keep order.

Population size
Subset size

Step-by-step solved example

How many 3-person crews from 8 workers?

μz
Counting C(n,k) feeds the binomial that becomes normal for large n.

  1. 1. Combination

    C(8,3)=8!/(3!5!)=56.

  2. 2. Not permutations

    Order in a crew does not matter, so do not use P(8,3)=336.

Answer: 56 crews

10 practice questions

0/10 correct

1.C(5,2) =

2.P(n,k)/C(n,k) equals

3.C(n,0) =

4.C(n,k)=C(n,n−k) is

5.Binomial n=4, p=0.5, P(X=2) uses C(4,2)=

6.C(10,10) =

7.P(6,2) =

8.If order of inspection of 3 sites among 9 matters, use

9.C(7,3) =

10.0! in the handbook is