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Statistics and Probability — High School Algebra 2 practice questions

16 multiple-choice questions and 5 flashcards on Statistics and Probability, about 11% of the High School Algebra 2 bank. Every one carries a written rationale.

Written and maintained by the CoStudy team · last updated 2026-10-12 · how we write and review questions

What this chapter covers

Statistics and Probability is one of 9 chapters in CoStudy's High School Algebra 2 bank, and it holds 16 of the bank's 150 multiple-choice questions — roughly 11% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.

Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.

Free Statistics and Probability practice questions

2 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.

Two cards are drawn without replacement. What is P(both hearts)?

  1. 1/16
  2. 1/4
  3. 1/17
  4. 12/51

Answer: C — 1/17

C) Correct — (13/52)(12/51) = 156/2652. A) Uses (1/4)(1/4), as if the card were replaced. B) Gives the probability for one card. D) Gives only the second-draw probability.

IQ scores are normal with mean 100 and standard deviation 15. What is the z-score for 130?

  1. 30
  2. 2
  3. 0.5
  4. 8.67

Answer: B — 2

B) Correct — z = (130 − 100)/15. A) Forgets to divide by σ. C) Divides σ by the difference. D) Divides 130 by 15.

Statistics and Probability flashcards

3 cards from the 5 in this chapter.

Worked Example: Compute C(8, 3) and use it: in a normal distribution with μ = 70, σ = 5, find the probability that a value is less than 80.

Part A — Combination C(8, 3). Step 1: Formula C(n, r) = n!/(r!(n − r)!). Step 2: Plug in n = 8, r = 3. C(8, 3) = 8!/(3!·5!) = (8·7·6)/(3·2·1) = 336/6 = 56. Part B — Normal distribution probability. Step 1: Compute the z-score. z = (x − μ)/σ = (80 − 70)/5 = 10/5 = 2. Step 2: Look up Φ(2) in the standard normal table. Φ(2) ≈ 0.9772 Step 3: Interpret. P(X < 80) = P(Z < 2) ≈ 0.9772, i.e., about 97.72%. Final answers: C(8, 3) = 56; P(X < 80) ≈ 0.9772.

Binomial probability formula?

P(exactly k successes in n trials) = C(n, k) · pᵏ · (1 − p)ⁿ⁻ᵏ.

Permutation vs combination?

Permutation: order matters, P(n, r) = n!/(n − r)!. Combination: order doesn't matter, C(n, r) = n!/(r!(n − r)!).

Practise the full chapter

These are a sample. The full Statistics and Probability chapter runs 21 items with per-chapter progress tracking, on the web and in the iOS app.

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