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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 381 · 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) less code to write (b) it is slower (c) it hides them (d) it uses more lines
  2. 2.🔁 What number does this code show?
    let marks = [92, 63, 94, 48, 90];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What number does this code show?
    let runs = [11, 2, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let runs = [44, 16, 54, 77];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What number does this code show?
    let runs = [5, 5, 4, 4, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let steps = [14, 66, 60, 49];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 list.length tells you ___. (a) the first item (b) the last item (c) how many items it has (d) the biggest item
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Meera
  9. 9.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 1 (c) 4 (d) 6
  10. 10.🔁 What number does this code show?
    let runs = [22, 85, 40, 19];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What number does this code show?
    let scores = [48, 11, 50, 11, 16];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  12. 12.🔁 What number does this code show?
    let steps = [13, 2, 20, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  13. 13.🔁 What does a loop do? (a) repeats code (b) draws icons (c) saves photos (d) deletes code
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Riya
  15. 15.🔁 What number does this code show?
    let scores = [26, 92, 79, 58];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let marks = [15, 27, 35, 28];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Arjun
  18. 18.🔁 What number does this code show?
    let runs = [5, 10, 15, 20, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Zoya
  21. 21.🔁 What number does this code show?
    let scores = [2, 4, 7, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  22. 22.🔁 What number does this code show?
    let scores = [42, 84, 58];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let runs = [8, 15, 20];
    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 steps = [2, 6, 5, 20, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Kabir (d) Hi, Riya
  26. 26.🔁 What number does this code show?
    let scores = [14, 3, 13, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let steps = [15, 4, 3, 17, 12];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let scores = [13, 18, 19, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let scores = [10, 20, 14, 20, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let steps = [89, 51, 79, 45];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2 (b) 0, 1, 2, 3 (c) 1, 2, 3 (d) 3
  32. 32.🔁 What number does this code show?
    let marks = [1, 9, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let scores = [94, 53, 78, 49];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let steps = [2, 20, 3, 6, 7];
    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 steps = [16, 12, 13, 8];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let scores = [4, 1, 15, 19, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let steps = [11, 3, 5, 18];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  38. 38.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Aman (d) Hi, Kabir
  39. 39.🔁 What number does this code show?
    let steps = [17, 7, 1, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let marks = [1, 20, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);

Answer key

  1. less code to write
  2. 4
  3. 27
  4. 1
  5. 12
  6. 3
  7. how many items it has
  8. Hi, Arjun
  9. 5
  10. 1
  11. 2
  12. 20
  13. repeats code
  14. Hi, Riya
  15. 2
  16. 0
  17. Hi, Aman
  18. 58
  19. Hi, Kabir
  20. Hi, Kabir
  21. 15
  22. 2
  23. 43
  24. 20
  25. Hi, Kabir
  26. 49
  27. 17
  28. 19
  29. 84
  30. 2
  31. 0, 1, 2
  32. 15
  33. 4
  34. 20
  35. 49
  36. 50
  37. 37
  38. Hi, Riya
  39. 32
  40. 20

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