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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 980 · 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.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) less code to write (d) it is slower
  2. 2.🔁 What number does this code show?
    let runs = [21, 89, 98, 14, 12];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What number does this code show?
    let scores = [86, 18, 28];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 What number does this code show?
    let runs = [20, 9, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  5. 5.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Meera", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Meera (d) Hi, Riya
  6. 6.🔁 list.length tells you ___. (a) the first item (b) how many items it has (c) the last item (d) the biggest item
  7. 7.🔁 What number does this code show?
    let scores = [13, 16, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  8. 8.🔁 What does a loop do? (a) repeats code (b) saves photos (c) draws icons (d) deletes code
  9. 9.🔁 What number does this code show?
    let runs = [2, 10, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Riya
  11. 11.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 6 (c) 1 (d) 5
  12. 12.🔁 What number does this code show?
    let scores = [8, 8, 5, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  13. 13.🔁 What number does this code show?
    let scores = [13, 19, 1, 17];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let marks = [19, 10, 7, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  15. 15.🔁 What number does this code show?
    let scores = [9, 12, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let runs = [2, 17, 2];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let marks = [7, 20, 14];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  18. 18.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 1, 2, 3
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir
  20. 20.🔁 What number does this code show?
    let runs = [20, 4, 7, 3, 14];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Zoya
  22. 22.🔁 What number does this code show?
    let scores = [65, 34, 90, 98, 95];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let runs = [17, 5, 11, 17, 16];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let steps = [6, 10, 3];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let scores = [5, 5, 17];
    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 = [55, 12, 59];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let marks = [19, 11, 2, 8, 14];
    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 scores = [16, 16, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Arjun (d) Hi, Riya
  30. 30.🔁 What number does this code show?
    let marks = [16, 17, 6, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Meera
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Arjun (d) Hi, Kabir
  33. 33.🔁 What number does this code show?
    let marks = [8, 19, 17];
    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 steps = [33, 58, 11];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let runs = [17, 7, 16, 12, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let runs = [8, 9, 10];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  37. 37.🔁 What number does this code show?
    let steps = [12, 19, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let runs = [12, 36, 56];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera
  40. 40.🔁 What number does this code show?
    let scores = [5, 15, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);

Answer key

  1. less code to write
  2. 2
  3. 1
  4. 36
  5. Hi, Riya
  6. how many items it has
  7. 16
  8. repeats code
  9. 27
  10. Hi, Kabir
  11. 5
  12. 41
  13. 19
  14. 46
  15. 37
  16. 21
  17. 20
  18. 0, 1, 2
  19. Hi, Aman
  20. 20
  21. Hi, Zoya
  22. 4
  23. 66
  24. 19
  25. 27
  26. 0
  27. 19
  28. 40
  29. Hi, Zoya
  30. 56
  31. Hi, Aman
  32. Hi, Arjun
  33. 44
  34. 1
  35. 17
  36. 10
  37. 43
  38. 1
  39. Hi, Meera
  40. 15

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