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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 108 · 40 questions
TalentJR

Developer's tip (One by one): for (let i = 0; i < list.length; i++) visits every item, from position 0. Total: add each item. Count: add 1 when the test is true. Best: keep the biggest so far. The body runs once per item: a list of 5 runs it 5 times.

NameDateTime takenScore ___ / 40
  1. 1.🔁 What number does this code show?
    let scores = [7, 5, 3, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Meera", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Meera (d) Hi, Arjun
  3. 3.🔁 What number does this code show?
    let scores = [12, 6, 19, 1, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let marks = [86, 42, 18, 98];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 list.length tells you ___. (a) how many items it has (b) the first item (c) the last item (d) the biggest item
  6. 6.🔁 What number does this code show?
    let steps = [14, 18, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let steps = [6, 9, 1, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  8. 8.🔁 What number does this code show?
    let runs = [97, 94, 31];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What number does this code show?
    let runs = [55, 26, 44];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let marks = [2, 12, 19, 10, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  11. 11.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 6 (d) 5
  12. 12.🔁 What number does this code show?
    let scores = [5, 3, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  13. 13.🔁 What number does this code show?
    let steps = [91, 56, 29];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Arjun (d) Hi, Zoya
  15. 15.🔁 What number does this code show?
    let marks = [5, 10, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let marks = [8, 13, 5, 19];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let marks = [8, 14, 1, 4, 19];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  18. 18.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2, 3 (c) 0, 1, 2 (d) 1, 2, 3
  19. 19.🔁 What does a loop do? (a) draws icons (b) deletes code (c) repeats code (d) saves photos
  20. 20.🔁 What number does this code show?
    let scores = [62, 80, 72];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let runs = [17, 15, 20, 1, 14];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let runs = [2, 17, 2, 2, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  23. 23.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it uses more lines (c) it hides them (d) less code to write
  24. 24.🔁 What number does this code show?
    let runs = [16, 30, 93, 73, 13];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let scores = [52, 43, 63];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let runs = [51, 16, 34, 54, 40];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let scores = [6, 14, 5, 19, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  28. 28.🔁 What number does this code show?
    let steps = [14, 13, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Kabir", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Aman
  30. 30.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Meera (d) Hi, Arjun
  31. 31.🔁 What number does this code show?
    let steps = [9, 11, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Aman", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
  33. 33.🔁 What number does this code show?
    let steps = [1, 6, 18, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let steps = [6, 1, 19, 16];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  35. 35.🔁 What number does this code show?
    let scores = [4, 16, 4, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let runs = [62, 44, 66, 66, 41];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let steps = [3, 3, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let marks = [34, 35, 75];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Aman
  40. 40.🔁 What number does this code show?
    let marks = [3, 2, 1, 14, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);

Answer key

  1. 19
  2. Hi, Arjun
  3. 52
  4. 2
  5. how many items it has
  6. 37
  7. 9
  8. 2
  9. 2
  10. 19
  11. 5
  12. 18
  13. 1
  14. Hi, Meera
  15. 20
  16. 45
  17. 19
  18. 0, 1, 2
  19. repeats code
  20. 3
  21. 20
  22. 35
  23. less code to write
  24. 2
  25. 3
  26. 3
  27. 64
  28. 14
  29. Hi, Meera
  30. Hi, Meera
  31. 11
  32. Hi, Riya
  33. 27
  34. 19
  35. 16
  36. 5
  37. 8
  38. 1
  39. Hi, Riya
  40. 24

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