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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 610 · 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 steps = [1, 15, 5, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Zoya (d) Hi, Riya
  3. 3.🔁 What number does this code show?
    let steps = [9, 2, 2, 6, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let scores = [2, 14, 13, 8, 6];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  5. 5.🔁 What number does this code show?
    let runs = [19, 33, 69, 31, 65];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Meera
  7. 7.🔁 What number does this code show?
    let scores = [11, 15, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  8. 8.🔁 What does a loop do? (a) saves photos (b) draws icons (c) repeats code (d) deletes code
  9. 9.🔁 What number does this code show?
    let steps = [12, 20, 17, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  10. 10.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 1 (c) 5 (d) 6
  11. 11.🔁 What number does this code show?
    let steps = [20, 23, 24, 21, 97];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  12. 12.🔁 What number does this code show?
    let marks = [19, 14, 15, 16];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  13. 13.🔁 What number does this code show?
    let steps = [6, 11, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let scores = [43, 16, 39, 73];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Arjun (d) Hi, Riya
  16. 16.🔁 What number does this code show?
    let steps = [5, 6, 3];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  17. 17.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2 (c) 0, 1, 2, 3 (d) 3
  18. 18.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) less code to write (c) it is slower (d) it hides them
  19. 19.🔁 What number does this code show?
    let steps = [10, 13, 7];
    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 steps = [1, 11, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  21. 21.🔁 list.length tells you ___. (a) the first item (b) the last item (c) how many items it has (d) the biggest item
  22. 22.🔁 What number does this code show?
    let runs = [99, 77, 99, 64, 59];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let marks = [70, 54, 73, 34];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let scores = [9, 3, 12, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let steps = [19, 15, 13, 10, 8];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let runs = [14, 14, 9, 13];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let runs = [4, 19, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  28. 28.🔁 What number does this code show?
    let marks = [15, 58, 62];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let marks = [14, 10, 15, 13];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  30. 30.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Arjun (d) Hi, Riya
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Kabir (d) Hi, Arjun
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Aman (d) Hi, Arjun
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Arjun
  34. 34.🔁 What number does this code show?
    let steps = [3, 14, 16, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let runs = [17, 60, 25, 20, 23];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let runs = [61, 93, 61];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let scores = [3, 14, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let runs = [84, 10, 57, 74, 38];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Kabir (d) Hi, Zoya
  40. 40.🔁 What number does this code show?
    let runs = [3, 9, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

Answer key

  1. 15
  2. Hi, Aman
  3. 20
  4. 43
  5. 2
  6. Hi, Meera
  7. 42
  8. repeats code
  9. 20
  10. 5
  11. 1
  12. 64
  13. 11
  14. 2
  15. Hi, Aman
  16. 14
  17. 0, 1, 2
  18. less code to write
  19. 30
  20. 19
  21. how many items it has
  22. 4
  23. 3
  24. 19
  25. 65
  26. 14
  27. 26
  28. 0
  29. 52
  30. Hi, Kabir
  31. Hi, Kabir
  32. Hi, Riya
  33. Hi, Arjun
  34. 34
  35. 1
  36. 1
  37. 18
  38. 2
  39. Hi, Meera
  40. 27

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