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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 67 · 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 is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Arjun
  2. 2.🔁 What number does this code show?
    let runs = [70, 64, 30, 64];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What number does this code show?
    let runs = [16, 11, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  4. 4.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 5 (c) 4 (d) 1
  5. 5.🔁 What number does this code show?
    let marks = [12, 14, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  6. 6.🔁 What number does this code show?
    let steps = [4, 19, 12, 9];
    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 marks = [6, 6, 3, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let marks = [5, 13, 6, 13, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  9. 9.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Riya (d) Hi, Aman
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Meera
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Aman (d) Hi, Kabir
  13. 13.🔁 What number does this code show?
    let marks = [66, 69, 78];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 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
  15. 15.🔁 What number does this code show?
    let steps = [3, 19, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  16. 16.🔁 What number does this code show?
    let runs = [2, 10, 9, 15, 9];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  17. 17.🔁 What number does this code show?
    let scores = [73, 96, 42];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let scores = [70, 37, 37];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Arjun
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Meera
  21. 21.🔁 What does a loop do? (a) deletes code (b) draws icons (c) repeats code (d) saves photos
  22. 22.🔁 What number does this code show?
    let steps = [17, 14, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Meera
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir
  25. 25.🔁 What number does this code show?
    let scores = [20, 19, 18, 9];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  26. 26.🔁 What number does this code show?
    let steps = [17, 6, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let marks = [90, 55, 13, 50, 36];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What number does this code show?
    let steps = [13, 94, 26, 20, 40];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let scores = [25, 35, 34];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it uses more lines (d) it is slower
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
  32. 32.🔁 What number does this code show?
    let scores = [36, 42, 93, 57, 66];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun
  34. 34.🔁 What number does this code show?
    let runs = [5, 18, 14, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  35. 35.🔁 What number does this code show?
    let steps = [2, 3, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let runs = [19, 27, 11, 17];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let steps = [35, 63, 68, 29];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let steps = [10, 2, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let steps = [5, 2, 11];
    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 scores = [43, 63, 62, 57, 86];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. Hi, Arjun
  2. 3
  3. 38
  4. 5
  5. 43
  6. 44
  7. 32
  8. 42
  9. how many items it has
  10. Hi, Aman
  11. Hi, Kabir
  12. Hi, Aman
  13. 3
  14. 0, 1, 2
  15. 19
  16. 15
  17. 3
  18. 1
  19. Hi, Kabir
  20. Hi, Arjun
  21. repeats code
  22. 20
  23. Hi, Kabir
  24. Hi, Riya
  25. 20
  26. 20
  27. 3
  28. 2
  29. 0
  30. less code to write
  31. Hi, Kabir
  32. 1
  33. Hi, Kabir
  34. 18
  35. 6
  36. 0
  37. 2
  38. 21
  39. 18
  40. 5

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