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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 329 · 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 marks = [6, 4, 1, 14];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  2. 2.🔁 What number does this code show?
    let scores = [58, 37, 50, 93, 64];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Meera"];
    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 scores = [95, 32, 37, 54, 60];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 list.length tells you ___. (a) the last item (b) the first item (c) the biggest item (d) how many items it has
  6. 6.🔁 What number does this code show?
    let marks = [11, 10, 23, 28];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let runs = [1, 9, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Riya (d) Hi, Arjun
  9. 9.🔁 What number does this code show?
    let steps = [13, 55, 75];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let steps = [4, 5, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Meera", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Meera
  12. 12.🔁 What number does this code show?
    let scores = [31, 83, 42];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Zoya (d) Hi, Kabir
  14. 14.🔁 What number does this code show?
    let steps = [57, 70, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let marks = [14, 15, 6, 6];
    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 marks = [18, 17, 1, 16, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  17. 17.🔁 What does a loop do? (a) deletes code (b) repeats code (c) draws icons (d) saves photos
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Aman
  19. 19.🔁 What number does this code show?
    let steps = [14, 14, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let runs = [12, 16, 1];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let runs = [18, 19, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  22. 22.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 5 (c) 4 (d) 6
  23. 23.🔁 What number does this code show?
    let scores = [34, 21, 55, 83, 90];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 3 (c) 1, 2, 3 (d) 0, 1, 2
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Meera", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
  26. 26.🔁 What number does this code show?
    let steps = [3, 5, 8, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Aman
  28. 28.🔁 What number does this code show?
    let steps = [17, 2, 13, 20, 19];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  29. 29.🔁 What number does this code show?
    let steps = [17, 2, 10, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  30. 30.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it is slower (c) less code to write (d) it uses more lines
  31. 31.🔁 What number does this code show?
    let runs = [5, 10, 15, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let marks = [15, 17, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Riya", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya (d) Hi, Zoya
  34. 34.🔁 What number does this code show?
    let marks = [55, 60, 66];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Riya (d) Hi, Meera
  36. 36.🔁 What number does this code show?
    let steps = [1, 8, 2, 3];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let steps = [85, 90, 89, 86, 36];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let runs = [5, 14, 20];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let runs = [13, 8, 1, 19];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let steps = [83, 76, 64, 13, 85];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 25
  2. 4
  3. Hi, Meera
  4. 1
  5. how many items it has
  6. 0
  7. 9
  8. Hi, Riya
  9. 1
  10. 29
  11. Hi, Riya
  12. 1
  13. Hi, Riya
  14. 2
  15. 15
  16. 18
  17. repeats code
  18. Hi, Zoya
  19. 44
  20. 16
  21. 49
  22. 5
  23. 2
  24. 0, 1, 2
  25. Hi, Aman
  26. 8
  27. Hi, Kabir
  28. 71
  29. 17
  30. less code to write
  31. 42
  32. 36
  33. Hi, Zoya
  34. 3
  35. Hi, Kabir
  36. 14
  37. 4
  38. 20
  39. 41
  40. 4

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