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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 619 · 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 does a loop do? (a) saves photos (b) deletes code (c) draws icons (d) repeats code
  2. 2.🔁 What number does this code show?
    let runs = [21, 88, 36];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What number does this code show?
    let steps = [3, 15, 4];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  4. 4.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Zoya
  5. 5.🔁 What number does this code show?
    let marks = [17, 10, 8, 10, 17];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let scores = [17, 4, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let marks = [9, 14, 7, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  8. 8.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 1, 2, 3 (c) 0, 1, 2, 3 (d) 0, 1, 2
  9. 9.🔁 What number does this code show?
    let scores = [28, 47, 67, 45];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let runs = [16, 4, 5, 20, 18];
    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) 1 (c) 6 (d) 5
  12. 12.🔁 What number does this code show?
    let runs = [12, 6, 19, 9, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  13. 13.🔁 What number does this code show?
    let steps = [15, 7, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  14. 14.🔁 What number does this code show?
    let marks = [55, 22, 59, 74];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Zoya
  16. 16.🔁 What number does this code show?
    let scores = [34, 77, 22];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let scores = [21, 33, 10, 28];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let runs = [31, 10, 22];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let runs = [1, 11, 5, 3, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let scores = [9, 5, 16, 7];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let runs = [81, 24, 46, 20, 88];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let scores = [19, 3, 10, 9, 16];
    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 scores = [16, 15, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let runs = [42, 37, 21, 85, 60];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let marks = [21, 76, 45, 57];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Aman", "Zoya", "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
  27. 27.🔁 What number does this code show?
    let scores = [5, 20, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  28. 28.🔁 list.length tells you ___. (a) the last item (b) the first item (c) how many items it has (d) the biggest item
  29. 29.🔁 What number does this code show?
    let scores = [93, 42, 62, 77];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let steps = [6, 8, 20, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  31. 31.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it uses more lines (c) less code to write (d) it is slower
  32. 32.🔁 What number does this code show?
    let runs = [12, 3, 3, 16, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Arjun
  34. 34.🔁 What number does this code show?
    let runs = [17, 19, 9, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let scores = [17, 17, 15, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Aman", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Aman
  37. 37.🔁 What number does this code show?
    let scores = [13, 11, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let runs = [17, 11, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let runs = [87, 84, 49, 45];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Meera (d) Hi, Riya

Answer key

  1. repeats code
  2. 1
  3. 15
  4. Hi, Zoya
  5. 17
  6. 38
  7. 14
  8. 0, 1, 2
  9. 0
  10. 63
  11. 5
  12. 63
  13. 24
  14. 1
  15. Hi, Aman
  16. 1
  17. 0
  18. 0
  19. 33
  20. 16
  21. 3
  22. 57
  23. 40
  24. 2
  25. 1
  26. Hi, Riya
  27. 30
  28. how many items it has
  29. 4
  30. 20
  31. less code to write
  32. 47
  33. Hi, Zoya
  34. 53
  35. 17
  36. Hi, Arjun
  37. 28
  38. 39
  39. 2
  40. Hi, Meera

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