IB Math TI-84 Reference Guide — AA & AI

The TI-84 Plus CE is approved for all IB Math papers that permit a GDC (Graphic Display Calculator). This guide covers the functions you'll actually use — organized by IB Math course.

AA vs AI: Which Functions Do You Need?

IB Math has two pathways. Your calculator use differs significantly between them:

AA students use the TI-84 mostly for calculus and normal distribution. AI students use it heavily for statistics — regression, tests, and distributions.

Normal Distribution — normalcdf and invNorm

These are the most-used functions across both AA and AI.

normalcdf — finding a probability

Finds the probability that X falls between two values.

Syntax: normalcdf(lower, upper, μ, σ)

Steps:

1. Press 2ND → VARS to open DISTR
2. Select 2: normalcdf(
3. Enter: normalcdf(lower, upper, μ, σ) → ENTER

IB examples:

Use -1E99 for negative infinity and 1E99 for positive infinity. Press 2ND → , for the E key.

invNorm — finding a value from a probability

Finds the x-value where the cumulative probability equals p.

Syntax: invNorm(area, μ, σ)

Steps:

1. Press 2ND → VARS → 3: invNorm(
2. Enter: invNorm(probability, μ, σ) → ENTER

IB example: Find k such that P(X < k) = 0.90, where μ=65, σ=8. Entry: invNorm(0.90, 65, 8) → 75.25

invNorm always takes the left-tail area. If the question gives P(X > k) = 0.10, enter invNorm(0.90, 65, 8) — convert to left-tail first.

Binomial Distribution — binompdf and binomcdf

binompdf — exact probability P(X = k)

Syntax: binompdf(n, p, k)

Example: 10 trials, p = 0.3, find P(X = 4). binompdf(10, 0.3, 4) → 0.2001

binomcdf — cumulative probability P(X ≤ k)

Syntax: binomcdf(n, p, k)

Example: Same setup, find P(X ≤ 4). binomcdf(10, 0.3, 4) → 0.8497

For P(X ≥ k): use 1 - binomcdf(n, p, k-1) For P(X > k): use 1 - binomcdf(n, p, k)

Calculus Functions (AA only)

nDeriv — numerical derivative

Finds the approximate derivative of f(x) at a specific point.

Syntax: nDeriv(expression, X, value)

1. Press MATH → 8: nDeriv(
2. Enter: nDeriv(X²+3X, X, 2) → ENTER
3. Result: 7 (derivative of x²+3x at x=2 is 2(2)+3=7 ✓)

nDeriv gives a numerical approximation, not an exact symbolic answer. For IB Paper 2, this is acceptable. For Paper 1 (no calculator), you must show working.

fnInt — numerical integral (definite integral)

Finds the area under a curve between two bounds.

Syntax: fnInt(expression, X, lower, upper)

1. Press MATH → 9: fnInt(
2. Enter: fnInt(X²+1, X, 0, 3) → ENTER
3. Result: 12 (∫₀³ (x²+1)dx = [x³/3 + x]₀³ = 9+3 = 12 ✓)

Linear Regression (AI only)

See the full step-by-step guide: Linear Regression on TI-84

Quick steps for AI exams:

1. Enter data: STAT → 1: Edit → L1 (x-values), L2 (y-values)
2. Run: STAT → CALC → 4: LinReg(ax+b)
3. Enable r and r²: Run DiagnosticOn from the CATALOG first (one-time setup)

IB AI output to know:

• a = slope (gradient of regression line)
• b = y-intercept
• r = correlation coefficient (IB asks you to "comment on r")
• r² = coefficient of determination

χ² Test for Independence (AI only)

Used when testing whether two categorical variables are independent.

Before you start: Enter your observed frequencies as a matrix.

1. Press 2ND → x⁻¹ to open MATRIX
2. Arrow right to EDIT → select [A]
3. Set matrix dimensions (rows × columns matching your contingency table)
4. Enter observed frequencies
5. Press STAT → TESTS → C: χ²-Test
6. Set Observed: [A], Expected: [B]
7. Select Calculate → ENTER

Output:

• χ² = test statistic
• p = p-value — compare to significance level
• df = degrees of freedom = (rows−1)(columns−1)

IB conclusion sentence:

"Since p = [value] < 0.05, we reject H₀. There is sufficient evidence that [variable 1] and [variable 2] are not independent."

Hypothesis Tests (AI HL and AA HL)

For T-Test and Z-Test step-by-step instructions, see: Hypothesis Testing on TI-84

For Confidence Intervals, see: Confidence Intervals on TI-84

GDC Exam Strategy for IB

What the IB expects from GDC use:

• Show what you entered and what output you used — write normalcdf(-∞, 70, 65, 8) = 0.734 not just = 0.734
• For regression, write the equation clearly: ŷ = 6.4x + 51.2
• For hypothesis tests, always state H₀ and H₁ before calculating, and include p-value in your conclusion
• Paper 2 / Paper 3 allow GDC — Paper 1 does not

Approved GDC for IB Math: The TI-84 Plus CE is approved for IB Math Papers 2 and 3 (both AA and AI). Confirm with your IB coordinator that no additional restrictions apply at your school.

Practice every function in this guide on the free TI-84 calculator.

Open TI-84 Calculator →

Related Guides

• Hypothesis Testing on TI-84 — Z-Test, T-Test & Proportion Test
• Confidence Intervals on TI-84 — ZInterval, TInterval & More
• Linear Regression on TI-84 — LinReg Step by Step