Permutation, Combination, Independent, and Dependent

From a group of 4 boys and 3 girls, in how many ways can we form a group 3 with at least 2 girls?

• 35

• 13

• 12

• 19

A student has to answer 8 questions in a 10-question test. If she has to answer at least 3 questions of the first 4, in how many ways can she select the questions?

• 44

• 45

• 39

• 24

₇P₂

• 0

• 7

• 42

• 210

₈P₃

• 1

• 8

• 56

• 336

₁₂C₃

• 36

• 66

• 220

• 500

I want to arrange 5 people in a row out of a class of 10 people. Number of ways = 

• 10P5

• 10C5

• 10!/(5!)

• 10!-5!

The word "arrange" usually refers to

• Permutation

• Combination

• Probability

• Counting

Permutation is the situation when

• different result occurs when positions of objects are switched

• same result occurs when positions of objects are switched

• counting principles are applied

• I don't know

Combination is the situation when

• A different result occurs when positions of objects are switched

• The same result occurs when positions of objects are switched

• counting principles are applied

• I don't know

When do we use the formula "n!/(a!*b!*...)"?

• Permutation. All objects distinct

• Permutation. Some identical objects

• Arranging people in a row

• Forming a group of r objects