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Single Variable Calculus
Differentiation
01The Derivative as the Slope of the Tangent Line02Secant Lines and the Limit Definition of the Derivative03Differentiating 1/x Straight From the Definition04Tangents to 1/x and the Triangle of Area 205Newton and Leibniz Notation, and the Power RuleProblem setProblem set 2MIT problem set
01The Derivative as an Instantaneous Rate of Change02Rates of Change Without Time: Gradient and Sensitivity03Easy Limits, 0/0, and One-Sided Limits04Continuity, Jumps, and Removable Discontinuities05Infinite Discontinuities: 1/x and Its Derivative06Differentiable Implies ContinuousProblem setProblem set 2
01Two Kinds of Formula, and the Derivative of Sine02The Derivative of Cosine, and Two Limits at Zero03Bow and Bowstring: Proving the Two Trig Limits04Why the Trig Derivatives Hold Only in Radians05A Geometric Proof: Sine as a Height on the Circle06Finishing the Proof, and the Product and Quotient RulesProblem setProblem set 2MIT problem set
01Proving the Product Rule: Change One Factor at a Time02The Quotient Rule, and the Power Rule for Negative Exponents03The Chain Rule: Differentiating a Function of a Function04Higher Derivatives: The Sine Cycle and Three Notations05The nth Derivative of xⁿ Is n Factorial, by InductionProblem setProblem set 2MIT problem set
01The Power Rule for Rational Exponents02The Slope of a Circle, Two Ways03Implicit Differentiation of a Quartic Curve04Inverse Functions and the Reflection Across y = x05Derivatives of the Arctangent and ArcsineProblem setProblem set 2MIT problem set
01The Derivative of aˣ and the Mystery Number M(a)02Defining e by Slope One, and the Derivative of ln x03M(a) = ln a: Differentiating aˣ and xˣ04Why (1 + 1/n)ⁿ Approaches eProblem setProblem set 2MIT problem set
Applications of Differentiation
01Linear Approximation: A Curve Is Its Tangent Line02Five Linear Approximations at Zero03Combining Approximations, from Algebra to GPS Clocks04Quadratic Approximation: The Best-Fit ParabolaProblem setProblem set 2MIT problem set
01Linear Approximation as a Proportionality Rule02Quadratic Approximation: Why the ½, and Products03Curve Sketching: The Sign of f′ and Critical Points04Curve Sketching: Ends, Concavity and InflectionProblem setProblem set 2MIT problem set
01Sketching Without Critical Points: (x+1)/(x+2)02A Five-Step Curve-Sketching Scheme, Applied to x / ln x03x / ln x: Inflection Point and Where Max and Min Can OccurProblem setProblem set 2
01Two Squares From One Wire: The Critical Point Gives the Least Area02The Open Box of Fixed Volume: Least Material When x = 2y03Related Rates: The Police Radar and the Conical TankProblem setProblem set 2MIT problem set
01The Hanging Ring: Why the String Makes Equal Angles02Newton's Method: Tangent Lines That Find the Square Root of Five03Why Newton's Method Doubles Its Digits, and How It Fails04The Mean Value Theorem: Somewhere You Hit Your Average Speed05Positive Derivative Means Increasing: Proving eˣ Exceeds 1 + xProblem setProblem set 2MIT problem set
Integration
01Differentials: dy = f′(x) dx and the Cube Root of 64.102Antiderivatives Differ Only by a Constant03Integration by Substitution and Advanced GuessingProblem setProblem set 2MIT problem set
01Separation of Variables: dy/dx = −xy and the Bell Curve02General Solutions: Signs, Constants and Initial Conditions03Orthogonal Trajectories: Parabolas and Crossing EllipsesProblem setProblem set 2MIT problem set
01The Definite Integral: Area as a Limit of Rectangle Sums02Area Under y = x²: Squeezing the Sum of Squares03Sigma Notation and the Area Pattern: b, b²/2, b³/304Riemann Sums: the Definite Integral and a Year of LoansProblem setProblem set 2MIT problem set
01The Fundamental Theorem of Calculus: Area in One Line02Net Change and Signed Area: Integrating Velocity03Six Rules for Definite Integrals and Bounds on eᵇ04Substitution in Definite Integrals: Change the LimitsProblem setProblem set 2MIT problem set
01Average Rate Times Time: FTC Beats the Mean Value Theorem02Second Fundamental Theorem: Differentiate an Integral03Proving FTC1 and FTC2 with the Mean Value TheoremProblem setProblem set 2MIT problem set
Applications of Integration
01The Natural Log Defined as an Area Under 1/t02Functions With No Formula: erf, Fresnel and Li(x)03Setting Up the Area Between Two Curves04Vertical vs Horizontal Slices: One Region, Two IntegralsProblem setProblem set 2
01The Disk Method: Volume of a Ball and a Spherical Cap02The Shell Method: Volume of a Parabolic Cauldron03Units Matter: Why y = x² Is Not Scale-InvariantProblem setProblem set 2MIT problem set
01Average Value: Two Heights of a Semicircle02Weighted Averages: The Cauldron's Average Temperature03Probability as a Weighted Average: Part over WholeProblem setProblem set 2MIT problem set
01Probability as a Shell Volume: Hitting a Ring on a Dart Board02One Percent Risk: Calibrating the Dart Model from One Fact03The Trapezoidal Rule: The Average of Left and Right Riemann Sums04Simpson's Rule: Parabolas and the Weights 1, 4, 1Problem setProblem set 2MIT problem set

Probability as a Shell Volume: Hitting a Ring on a Dart Board

How does a ring on a dartboard turn into a shell-method volume, and why does the unknown constant c cancel out of the probability?


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Questions

Work each one out before you check it. Every question has a scratch pad and a calculator.

  1. Question 1

    Darts land with c e−r2c\,e^{-r^2}ce−r2 hits per unit area at distance rrr from the centre. Using the method of shells, the expected number of hits in the disc r<0.6r < 0.6r<0.6 is k ck\,ckc. Find kkk to three decimal places.

    k=k =k=
  2. Question 2

    In the same dart model, c e−r2c\,e^{-r^2}ce−r2 hits per unit area, a total of 400400400 darts land on the (idealised, unbounded) board. Find the constant ccc to two decimal places.

    c=c =c=
  3. Question 3

    In the dart model with c e−r2c\,e^{-r^2}ce−r2 hits per unit area, find the probability that a dart lands in the ring 0.3<r<0.90.3 < r < 0.90.3<r<0.9, to three decimal places.

    P=P =P=
  4. Question 4

    In the dart model with c e−r2c\,e^{-r^2}ce−r2 hits per unit area, find the radius RRR of the disc r<Rr < Rr<R that receives 75%75\%75% of the darts. Give RRR to three decimal places.

    R=R =R=
  5. Question 5

    A different thrower is modelled by c e−r2/2c\,e^{-r^2/2}ce−r2/2 hits per unit area. Using shells for the part and the whole, find the probability that a dart lands in the ring 1<r<31 < r < 31<r<3, to three decimal places.

    P=P =P=
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