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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 384 · 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 = [43, 23, 91];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 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
  3. 3.🔁 list.length tells you ___. (a) the last item (b) how many items it has (c) the first item (d) the biggest item
  4. 4.🔁 What number does this code show?
    let runs = [19, 5, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  5. 5.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Aman (d) Hi, Arjun
  6. 6.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 6 (d) 1
  7. 7.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it uses more lines (c) less code to write (d) it is slower
  8. 8.🔁 What number does this code show?
    let scores = [12, 18, 11, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  9. 9.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Arjun
  10. 10.🔁 What number does this code show?
    let runs = [16, 1, 1, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Aman", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Meera (d) Hi, Zoya
  12. 12.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2 (c) 1, 2, 3 (d) 0, 1, 2, 3
  13. 13.🔁 What number does this code show?
    let marks = [2, 1, 2, 13, 11];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let steps = [86, 84, 89];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What does a loop do? (a) saves photos (b) draws icons (c) repeats code (d) deletes code
  16. 16.🔁 What number does this code show?
    let marks = [7, 9, 13, 7, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  17. 17.🔁 What number does this code show?
    let scores = [12, 7, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Meera
  19. 19.🔁 What number does this code show?
    let marks = [99, 97, 48];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let scores = [18, 81, 65];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let scores = [18, 7, 5, 2];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let runs = [68, 73, 52];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let marks = [1, 2, 12, 14, 17];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  24. 24.🔁 What number does this code show?
    let scores = [73, 30, 22, 65];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Arjun
  26. 26.🔁 What number does this code show?
    let steps = [14, 18, 17, 4, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let marks = [20, 30, 24, 31, 77];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Aman (d) Hi, Zoya
  29. 29.🔁 What number does this code show?
    let marks = [14, 19, 2, 3, 19];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let steps = [14, 2, 12, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let runs = [8, 14, 20];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let steps = [31, 77, 60, 22, 51];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let runs = [6, 6, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let steps = [1, 2, 18];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Arjun", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya (d) Hi, Zoya
  36. 36.🔁 What number does this code show?
    let scores = [4, 16, 3];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let steps = [20, 5, 16, 12, 20];
    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 = [9, 2, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let marks = [11, 11, 4, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Meera

Answer key

  1. 1
  2. Hi, Zoya
  3. how many items it has
  4. 19
  5. Hi, Aman
  6. 5
  7. less code to write
  8. 18
  9. Hi, Arjun
  10. 28
  11. Hi, Meera
  12. 0, 1, 2
  13. 13
  14. 3
  15. repeats code
  16. 13
  17. 31
  18. Hi, Zoya
  19. 2
  20. 2
  21. 18
  22. 3
  23. 17
  24. 1
  25. Hi, Meera
  26. 18
  27. 1
  28. Hi, Arjun
  29. 19
  30. 14
  31. 20
  32. 2
  33. 13
  34. 21
  35. Hi, Zoya
  36. 23
  37. 73
  38. 20
  39. 32
  40. Hi, Meera

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