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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 176 · 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.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 1 (c) 6 (d) 5
  2. 2.🔁 list.length tells you ___. (a) the biggest item (b) how many items it has (c) the first item (d) the last item
  3. 3.🔁 What number does this code show?
    let marks = [18, 1, 18, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  4. 4.🔁 What number does this code show?
    let runs = [47, 21, 43, 82, 49];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What does a loop do? (a) repeats code (b) deletes code (c) draws icons (d) saves photos
  6. 6.🔁 What number does this code show?
    let runs = [6, 17, 20];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  7. 7.🔁 What number does this code show?
    let steps = [5, 5, 3, 2, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let runs = [15, 17, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  9. 9.🔁 What number does this code show?
    let scores = [51, 98, 42, 69];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let scores = [21, 77, 13, 74, 41];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What number does this code show?
    let marks = [93, 49, 39, 64];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Riya (d) Hi, Arjun
  13. 13.🔁 What number does this code show?
    let runs = [14, 18, 13, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let scores = [12, 9, 8, 20, 2];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  15. 15.🔁 What number does this code show?
    let marks = [6, 11, 12, 18, 15];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  16. 16.🔁 What number does this code show?
    let scores = [7, 3, 9, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  17. 17.🔁 What number does this code show?
    let scores = [9, 3, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Riya", "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
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Meera (d) Hi, Riya
  20. 20.🔁 What number does this code show?
    let steps = [26, 33, 60];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let steps = [6, 8, 5];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let runs = [92, 40, 25];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Arjun", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Arjun (d) Hi, Riya
  24. 24.🔁 What number does this code show?
    let steps = [20, 40, 18];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 1, 2, 3 (c) 3 (d) 0, 1, 2
  26. 26.🔁 What number does this code show?
    let marks = [10, 89, 21, 75, 14];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let scores = [57, 82, 51, 48, 62];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 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
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Riya
  30. 30.🔁 What number does this code show?
    let runs = [11, 2, 13, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Aman
  32. 32.🔁 What number does this code show?
    let runs = [32, 33, 46];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Meera
  34. 34.🔁 What number does this code show?
    let steps = [50, 57, 56];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman
  36. 36.🔁 What number does this code show?
    let marks = [23, 16, 25];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let runs = [4, 7, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let marks = [1, 7, 20];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let marks = [7, 18, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Riya

Answer key

  1. 5
  2. how many items it has
  3. 18
  4. 4
  5. repeats code
  6. 20
  7. 21
  8. 52
  9. 2
  10. 2
  11. 3
  12. Hi, Meera
  13. 18
  14. 20
  15. 18
  16. 20
  17. 17
  18. Hi, Aman
  19. Hi, Zoya
  20. 1
  21. 8
  22. 1
  23. Hi, Meera
  24. 0
  25. 0, 1, 2
  26. 2
  27. 1
  28. less code to write
  29. Hi, Aman
  30. 33
  31. Hi, Meera
  32. 0
  33. Hi, Kabir
  34. 0
  35. Hi, Aman
  36. 0
  37. 19
  38. 28
  39. 18
  40. Hi, Arjun

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