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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 310 · 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 = [14, 12, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  2. 2.🔁 What number does this code show?
    let scores = [24, 47, 53];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 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, Aman (b) Hi, Riya (c) Hi, Meera
  4. 4.🔁 What number does this code show?
    let marks = [3, 9, 3, 16];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  5. 5.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Meera
  6. 6.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun
  7. 7.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 6 (d) 1
  8. 8.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it hides them (c) it uses more lines (d) less code to write
  9. 9.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir
  10. 10.🔁 What number does this code show?
    let marks = [7, 20, 19];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  11. 11.🔁 What does a loop do? (a) draws icons (b) repeats code (c) saves photos (d) deletes code
  12. 12.🔁 What number does this code show?
    let scores = [9, 2, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Kabir (d) Hi, Aman
  14. 14.🔁 What number does this code show?
    let runs = [80, 86, 96, 89, 19];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let scores = [9, 18, 19, 1, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  16. 16.🔁 What number does this code show?
    let scores = [7, 17, 3, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let steps = [49, 54, 63];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let marks = [19, 9, 1, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  19. 19.🔁 What number does this code show?
    let marks = [12, 19, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let scores = [62, 13, 80, 22, 37];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let runs = [13, 6, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Aman
  23. 23.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) how many items it has (d) the first item
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Meera (d) Hi, Arjun
  25. 25.🔁 What number does this code show?
    let scores = [2, 6, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Riya
  27. 27.🔁 What number does this code show?
    let marks = [3, 4, 10];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let steps = [6, 10, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Meera
  30. 30.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Riya
  31. 31.🔁 What number does this code show?
    let steps = [7, 12, 2, 18, 15];
    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 steps = [2, 8, 5, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let runs = [15, 74, 25, 15, 71];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let marks = [35, 70, 10];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let scores = [2, 20, 5, 3];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let steps = [12, 4, 7, 15, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  37. 37.🔁 What number does this code show?
    let marks = [17, 7, 4, 2, 17];
    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 = [3, 14, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Arjun
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Meera (d) Hi, Kabir

Answer key

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

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