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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 842 · 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.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it is slower (d) it uses more lines
  2. 2.🔁 What number does this code show?
    let steps = [68, 80, 46];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What number does this code show?
    let marks = [29, 97, 63, 60, 67];
    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 = [18, 6, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  5. 5.🔁 What number does this code show?
    let scores = [36, 88, 61, 17];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Arjun
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Meera
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Kabir
  9. 9.🔁 What number does this code show?
    let scores = [1, 8, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Arjun
  11. 11.🔁 What does a loop do? (a) deletes code (b) repeats code (c) draws icons (d) saves photos
  12. 12.🔁 What number does this code show?
    let steps = [58, 30, 37];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  13. 13.🔁 What number does this code show?
    let scores = [16, 5, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  14. 14.🔁 What number does this code show?
    let steps = [11, 10, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  15. 15.🔁 What number does this code show?
    let scores = [4, 20, 4, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let marks = [12, 6, 20];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Zoya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Aman
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Riya
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Zoya (d) Hi, Riya
  20. 20.🔁 What number does this code show?
    let scores = [15, 15, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  21. 21.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 1 (c) 6 (d) 4
  22. 22.🔁 What number does this code show?
    let scores = [4, 17, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  23. 23.🔁 What number does this code show?
    let runs = [37, 20, 69, 30, 99];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let marks = [19, 14, 20, 14];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let scores = [42, 88, 11];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Aman", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Kabir (d) Hi, Aman
  27. 27.🔁 What number does this code show?
    let steps = [19, 1, 14, 6, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  28. 28.🔁 What number does this code show?
    let marks = [10, 18, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  29. 29.🔁 What number does this code show?
    let marks = [6, 5, 18, 4, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let scores = [19, 2, 10, 14, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let steps = [12, 16, 9, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let steps = [20, 14, 31];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let marks = [86, 49, 81, 55, 80];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let steps = [15, 15, 10, 8, 19];
    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 = [23, 71, 48];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let steps = [79, 69, 14];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 3 (d) 0, 1, 2
  38. 38.🔁 What number does this code show?
    let scores = [6, 18, 10, 19, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let marks = [76, 32, 13, 13, 70];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let marks = [11, 46, 80, 61];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. less code to write
  2. 2
  3. 1
  4. 40
  5. 2
  6. Hi, Arjun
  7. Hi, Riya
  8. Hi, Zoya
  9. 21
  10. Hi, Arjun
  11. repeats code
  12. 0
  13. 22
  14. 20
  15. 48
  16. 20
  17. Hi, Aman
  18. Hi, Meera
  19. Hi, Aman
  20. 15
  21. 5
  22. 17
  23. 2
  24. 67
  25. 2
  26. Hi, Riya
  27. 44
  28. 33
  29. 50
  30. 19
  31. 16
  32. 0
  33. 3
  34. 67
  35. 1
  36. 1
  37. 0, 1, 2
  38. 54
  39. 2
  40. 1

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