Reading Questions Answer Checker
To check your answers put them in the appropriate box and click the ‘Check’ button. Every checker box can do arithmetic and calculate standard functions (see calculator help). If you give decimal answers, give them to at least 3 decimal places.
As you work you should have pencil and paper handy for calculations and thinking!
Note: some questions ask for a formula. For the checker we ask you to plug a value into the formula. For your pset you still need to give the whole formula.
//DEBUG PARAMETERS //Because we don’t show solutions for pset checkers we use //this to give a showanswer button during the debugging phase var debugans = undefined; //release //var debugans = kDebugAnswer; //debug problemNumber = 0; wl(“Calculator”); writecalculator(“psetcheckcalcid”, “Calculate”); whr(kdivcol,kdivwid);
//Problem 1 problemNumber++; wl(problemheader(problemNumber)); var s; var partName, problemName, buttonLabel, answerArray, correct; s = [“A random variable $X$ takes values $1$, $2$ and $4$ with probabilities $0.2$, $0.3$ and $0.5$ respectively.", kp, “What is Var$(X)$?"]; wl(s.join(’ ‘)); wl(kp); partName = problemNumber; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; writeNumericBox(partName+"id”, 1.56, buttonLabel, 0.01, kuseCorrectVal); whr(kdivcol,kdivwid);
//Problem 2 problemNumber++; wl(problemheader(problemNumber)); var s; var partName, problemName, buttonLabel, answerArray, correct; s = “Suppose $X$ has mean 2 and variance 3. Compute the following.” wl(s); wl(kp); s = ["(a) Var$(3X)$”]; wl(s.join(’ ‘)); wl(kp); partName = problemNumber + " (a)"; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; writeNumericBox(partName+"id”, 27, buttonLabel, 0.01, kuseCorrectVal); wl(kp); s = ["(b) Var$(3X+8)$”]; wl(s.join(’ ‘)); wl(kp); partName = problemNumber + " (b)"; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; writeNumericBox(partName+"id”, 27, buttonLabel, 0.01, kuseCorrectVal); wl(kp); s = ["(c) $E(X^2)$”]; wl(s.join(’ ‘)); wl(kp); partName = problemNumber + " (c)"; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; writeNumericBox(partName+"id”, 7, buttonLabel, 0.01, kuseCorrectVal); whr(kdivcol,kdivwid);
//Problem 3 problemNumber++; wl(problemheader(problemNumber)); var s; var partName, problemName, buttonLabel, answerArray, correct; s = “For the same random variable as in problem 2."; wl(s) wl(kp); s = “(a) Var$(X^2)$ = “; wl(s) wl(kbr) partName = problemNumber + " (a)"; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; correct = “Cannot be computed from the information given” var answerArray = [“13”, “9”, “5”, correct]; writeMultipleChoiceRadioGroup(answerArray, problemName, correct, buttonLabel); wl(kp); s = “(b) Can $X$ take negative values?"; wl(s) wl(kbr) partName = problemNumber + " (b)"; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; correct = “Yes” var answerArray = [correct, “No”]; writeMultipleChoiceRadioGroup(answerArray, problemName, correct, buttonLabel); whr(kdivcol,kdivwid);
//Problem 4 problemNumber++; wl(problemheader(problemNumber)); var s; var partName, problemName, buttonLabel, answerArray, correct; s = ["(a) True or false:", kp, “$E(X+Y) = E(X) + E(Y)$ for any random variables $X$ and $Y$."]; wl(s.join(’ ‘)); wl(kbr); partName = problemNumber + " (a)"; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; correct = “True” var answerArray = [correct, “False”]; writeMultipleChoiceRadioGroup(answerArray, problemName, correct, buttonLabel); wl(kp); s = ["(b) True or false:", kp, “Var$(X+Y) = $Var$(X) + $Var$(Y)$ for any random variables $X$ and $Y$."]; wl(s.join(’ ‘)); wl(kbr); partName = problemNumber + " (b)"; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; correct = “False” var answerArray = [“True”,correct]; writeMultipleChoiceRadioGroup(answerArray, problemName, correct, buttonLabel); whr(kdivcol,kdivwid);
//Problem 5 problemNumber++; wl(problemheader(problemNumber)); var s; var partName, problemName, buttonLabel, answerArray, correct; s = “$X ∼ $ Bernoulli(.8). What is the standard deviation of $X$?"; wl(s) wl(kp); partName = problemNumber; problemName = “prob” + partName; buttonLabel = “Check problem " + partName; writeNumericBox(partName+"id”, 0.4, buttonLabel, 0.01, kuseCorrectVal); wl(kp); whr(kdivcol,kdivwid);