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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 729 · 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 = [27, 41, 38];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What number does this code show?
    let steps = [1, 16, 3];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  3. 3.🔁 What number does this code show?
    let marks = [51, 30, 50];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 What number does this code show?
    let steps = [5, 9, 14, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  5. 5.🔁 list.length tells you ___. (a) the last item (b) how many items it has (c) the biggest item (d) the first item
  6. 6.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Aman
  7. 7.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it uses more lines (c) less code to write (d) it hides them
  8. 8.🔁 What does a loop do? (a) draws icons (b) repeats code (c) saves photos (d) deletes code
  9. 9.🔁 What number does this code show?
    let steps = [79, 54, 31];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let runs = [3, 12, 2, 18, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  11. 11.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 1 (d) 6
  12. 12.🔁 What number does this code show?
    let steps = [10, 12, 15, 7, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  13. 13.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2 (c) 1, 2, 3 (d) 0, 1, 2, 3
  14. 14.🔁 What number does this code show?
    let steps = [12, 20, 7, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Meera", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Meera (d) Hi, Kabir
  16. 16.🔁 What number does this code show?
    let marks = [11, 7, 18, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya (d) Hi, Arjun
  18. 18.🔁 What number does this code show?
    let runs = [39, 75, 32, 42, 79];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Meera
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Meera", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Riya (d) Hi, Aman
  21. 21.🔁 What number does this code show?
    let steps = [3, 16, 11, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  22. 22.🔁 What number does this code show?
    let scores = [12, 3, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let marks = [60, 14, 50, 69, 25];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let steps = [79, 34, 92];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let scores = [11, 15, 8, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Meera", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Meera
  27. 27.🔁 What number does this code show?
    let scores = [4, 16, 4];
    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 = [18, 3, 18, 8];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  29. 29.🔁 What number does this code show?
    let scores = [16, 13, 8, 6];
    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 scores = [33, 35, 68];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What number does this code show?
    let marks = [15, 15, 7, 6, 2];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let marks = [5, 5, 7, 5, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let runs = [66, 89, 36, 78];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let steps = [5, 20, 16];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Meera", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Meera (d) Hi, Aman
  36. 36.🔁 What number does this code show?
    let marks = [6, 12, 20, 7];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let scores = [31, 86, 60];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let steps = [14, 8, 15, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let runs = [13, 8, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let scores = [14, 4, 1, 14, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);

Answer key

  1. 1
  2. 20
  3. 0
  4. 45
  5. how many items it has
  6. Hi, Riya
  7. less code to write
  8. repeats code
  9. 2
  10. 47
  11. 5
  12. 15
  13. 0, 1, 2
  14. 59
  15. Hi, Zoya
  16. 54
  17. Hi, Meera
  18. 2
  19. Hi, Kabir
  20. Hi, Riya
  21. 42
  22. 32
  23. 2
  24. 2
  25. 43
  26. Hi, Riya
  27. 24
  28. 47
  29. 16
  30. 1
  31. 15
  32. 7
  33. 3
  34. 20
  35. Hi, Aman
  36. 45
  37. 1
  38. 15
  39. 35
  40. 41

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