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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 458 · 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 steps = [19, 10, 5, 9, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Zoya (d) Hi, Riya
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Meera (d) Hi, Zoya
  4. 4.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 0, 1, 2 (c) 1, 2, 3 (d) 3
  5. 5.🔁 What number does this code show?
    let runs = [5, 12, 6, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  6. 6.🔁 What number does this code show?
    let marks = [20, 1, 18, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  7. 7.🔁 What number does this code show?
    let runs = [94, 49, 85];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What does a loop do? (a) draws icons (b) repeats code (c) deletes code (d) saves photos
  9. 9.🔁 What number does this code show?
    let scores = [17, 13, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  10. 10.🔁 What number does this code show?
    let scores = [1, 7, 16, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  11. 11.🔁 What number does this code show?
    let marks = [9, 4, 17, 4, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  12. 12.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it is slower (c) it uses more lines (d) less code to write
  13. 13.🔁 What number does this code show?
    let scores = [96, 51, 17, 86];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 list.length tells you ___. (a) the biggest item (b) the last item (c) the first item (d) how many items it has
  15. 15.🔁 What number does this code show?
    let runs = [11, 2, 12, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  16. 16.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 6 (c) 5 (d) 1
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya (d) Hi, Zoya
  18. 18.🔁 What number does this code show?
    let scores = [16, 15, 1, 3, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman (d) Hi, Arjun
  20. 20.🔁 What number does this code show?
    let steps = [6, 13, 18, 2, 9];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let runs = [2, 8, 6, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  22. 22.🔁 What number does this code show?
    let marks = [68, 82, 10, 27, 37];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let runs = [2, 12, 1, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let runs = [77, 43, 45, 53, 96];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Kabir
  26. 26.🔁 What number does this code show?
    let runs = [6, 13, 1, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Aman
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Riya", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Riya (d) Hi, Zoya
  29. 29.🔁 What number does this code show?
    let scores = [9, 7, 5, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let runs = [49, 50, 62, 58];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Zoya (d) Hi, Meera
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Arjun (d) Hi, Meera
  33. 33.🔁 What number does this code show?
    let steps = [29, 39, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let steps = [16, 10, 19, 1, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let scores = [13, 15, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman (d) Hi, Zoya
  37. 37.🔁 What number does this code show?
    let runs = [1, 5, 17, 7, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let scores = [2, 9, 4, 16, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let marks = [16, 18, 15, 4, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  40. 40.🔁 What number does this code show?
    let scores = [3, 7, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);

Answer key

  1. 48
  2. Hi, Zoya
  3. Hi, Meera
  4. 0, 1, 2
  5. 37
  6. 20
  7. 3
  8. repeats code
  9. 35
  10. 26
  11. 17
  12. less code to write
  13. 2
  14. how many items it has
  15. 36
  16. 5
  17. Hi, Zoya
  18. 19
  19. Hi, Aman
  20. 18
  21. 31
  22. 2
  23. 24
  24. 2
  25. Hi, Kabir
  26. 40
  27. Hi, Kabir
  28. Hi, Zoya
  29. 12
  30. 3
  31. Hi, Meera
  32. Hi, Zoya
  33. 0
  34. 47
  35. 15
  36. Hi, Aman
  37. 17
  38. 19
  39. 18
  40. 12

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