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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 97 · 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, 2, 11];
    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 runs = [9, 11, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Aman", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Riya (d) Hi, Meera
  4. 4.🔁 What number does this code show?
    let scores = [91, 61, 46];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        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 steps = [6, 10, 14, 12, 12];
    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 runs = [14, 17, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Zoya (d) Hi, Riya
  9. 9.🔁 What number does this code show?
    let steps = [18, 16, 15, 2, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  10. 10.🔁 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, Zoya (b) Hi, Riya (c) Hi, Aman
  11. 11.🔁 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
  12. 12.🔁 What number does this code show?
    let runs = [41, 64, 44, 92, 28];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  13. 13.🔁 What number does this code show?
    let scores = [9, 7, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  14. 14.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 0, 1, 2, 3
  15. 15.🔁 What number does this code show?
    let scores = [31, 75, 36];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 6 (d) 5
  17. 17.🔁 What number does this code show?
    let marks = [20, 5, 18, 9];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  18. 18.🔁 What number does this code show?
    let marks = [27, 74, 76, 56];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let scores = [16, 5, 18];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let steps = [13, 4, 9, 12, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  21. 21.🔁 What number does this code show?
    let runs = [16, 16, 16, 16, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let marks = [29, 23, 79, 13];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Arjun (d) Hi, Aman
  24. 24.🔁 What number does this code show?
    let runs = [88, 21, 34, 65];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let runs = [10, 10, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Riya
  27. 27.🔁 What number does this code show?
    let marks = [7, 3, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  28. 28.🔁 What number does this code show?
    let marks = [96, 71, 26, 11, 14];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
  30. 30.🔁 What number does this code show?
    let steps = [35, 89, 30, 20];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What number does this code show?
    let steps = [12, 16, 10];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let runs = [1, 14, 15, 16, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let runs = [20, 2, 13, 16, 15];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Riya (d) Hi, Meera
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Zoya
  36. 36.🔁 What number does this code show?
    let scores = [50, 52, 43, 35, 20];
    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 = [39, 68, 71, 39, 52];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let steps = [8, 13, 12, 4, 5];
    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 = [93, 57, 20, 14, 30];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let runs = [51, 86, 55, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 26
  2. 12
  3. Hi, Meera
  4. 2
  5. repeats code
  6. 54
  7. 48
  8. Hi, Riya
  9. 57
  10. Hi, Aman
  11. less code to write
  12. 2
  13. 33
  14. 0, 1, 2
  15. 1
  16. 5
  17. 20
  18. 2
  19. 39
  20. 58
  21. 16
  22. 1
  23. Hi, Aman
  24. 2
  25. 38
  26. Hi, Aman
  27. 22
  28. 2
  29. how many items it has
  30. 1
  31. 38
  32. 56
  33. 20
  34. Hi, Kabir
  35. Hi, Arjun
  36. 0
  37. 2
  38. 42
  39. 2
  40. 3

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