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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 798 · 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 number does this code show?
    let scores = [13, 3, 10, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  2. 2.🔁 What number does this code show?
    let scores = [6, 6, 20, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  3. 3.🔁 What number does this code show?
    let scores = [34, 89, 66, 93, 27];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 What number does this code show?
    let runs = [4, 3, 13];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  5. 5.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it uses more lines (d) it is slower
  6. 6.🔁 What number does this code show?
    let runs = [5, 14, 4, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let marks = [93, 58, 71];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What number does this code show?
    let marks = [17, 7, 17];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  9. 9.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 6 (d) 1
  10. 10.🔁 What number does this code show?
    let scores = [6, 13, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  11. 11.🔁 What does a loop do? (a) saves photos (b) repeats code (c) deletes code (d) draws icons
  12. 12.🔁 list.length tells you ___. (a) the first item (b) how many items it has (c) the last item (d) the biggest item
  13. 13.🔁 What number does this code show?
    let runs = [1, 17, 2, 16];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Meera", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Meera (d) Hi, Riya
  15. 15.🔁 What number does this code show?
    let marks = [2, 4, 14, 10];
    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 = [11, 56, 61, 63];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let steps = [11, 18, 5, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  18. 18.🔁 What number does this code show?
    let scores = [18, 17, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  19. 19.🔁 What number does this code show?
    let steps = [90, 65, 43];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Aman
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Aman", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Zoya
  22. 22.🔁 What number does this code show?
    let scores = [19, 18, 20, 9];
    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 scores = [18, 5, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  24. 24.🔁 What number does this code show?
    let scores = [95, 86, 14, 35];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let scores = [4, 16, 13];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let scores = [18, 15, 6];
    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 scores = [1, 13, 16];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Riya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Zoya
  29. 29.🔁 What number does this code show?
    let runs = [3, 7, 14, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let runs = [12, 7, 8, 14, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let steps = [16, 5, 3];
    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 scores = [16, 9, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let marks = [4, 12, 9, 8, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let runs = [69, 18, 37];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let runs = [26, 19, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let scores = [48, 90, 82, 20, 64];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let marks = [20, 3, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let marks = [12, 63, 10, 91];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let steps = [16, 4, 11, 17];
    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 = [5, 19, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);

Answer key

  1. 46
  2. 52
  3. 3
  4. 13
  5. less code to write
  6. 40
  7. 2
  8. 17
  9. 5
  10. 15
  11. repeats code
  12. how many items it has
  13. 36
  14. Hi, Kabir
  15. 14
  16. 3
  17. 18
  18. 18
  19. 2
  20. Hi, Arjun
  21. Hi, Riya
  22. 20
  23. 18
  24. 2
  25. 33
  26. 39
  27. 16
  28. Hi, Arjun
  29. 14
  30. 14
  31. 16
  32. 41
  33. 45
  34. 0
  35. 0
  36. 3
  37. 35
  38. 2
  39. 48
  40. 29

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