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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 250 · 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 is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Zoya
  2. 2.🔁 What number does this code show?
    let scores = [91, 65, 87, 17];
    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 = ["Aman", "Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Kabir
  4. 4.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it uses more lines (d) it is slower
  5. 5.🔁 What number does this code show?
    let scores = [21, 77, 19, 92, 50];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Riya", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya (d) Hi, Meera
  7. 7.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 6 (d) 1
  8. 8.🔁 What number does this code show?
    let scores = [12, 17, 10, 7, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  9. 9.🔁 What number does this code show?
    let scores = [75, 13, 40, 97, 50];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let marks = [16, 15, 77, 27];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 3 (c) 0, 1, 2 (d) 0, 1, 2, 3
  12. 12.🔁 What number does this code show?
    let runs = [98, 67, 64];
    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 steps = [34, 13, 34];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let scores = [38, 57, 89];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        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 = [12, 84, 77];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let runs = [13, 97, 22];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let runs = [55, 35, 35, 17, 33];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Riya
  20. 20.🔁 What number does this code show?
    let runs = [12, 19, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  21. 21.🔁 What number does this code show?
    let scores = [11, 10, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Riya
  23. 23.🔁 What number does this code show?
    let runs = [83, 66, 62, 20, 88];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let scores = [4, 4, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let scores = [8, 16, 4, 12, 4];
    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 = [11, 9, 17, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let steps = [1, 2, 15, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Aman (d) Hi, Kabir
  29. 29.🔁 What number does this code show?
    let marks = [40, 72, 46];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let steps = [2, 13, 9, 8];
    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 scores = [12, 6, 12, 14, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let runs = [13, 6, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Riya", "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
  34. 34.🔁 What number does this code show?
    let steps = [5, 17, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  35. 35.🔁 What number does this code show?
    let marks = [97, 11, 32, 92, 23];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let steps = [7, 18, 20, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Riya (d) Hi, Arjun
  38. 38.🔁 What number does this code show?
    let marks = [21, 36, 51, 86];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let scores = [13, 20, 9, 18, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Riya (d) Hi, Kabir

Answer key

  1. Hi, Arjun
  2. 3
  3. Hi, Kabir
  4. less code to write
  5. 3
  6. Hi, Arjun
  7. 5
  8. 56
  9. 3
  10. 1
  11. 0, 1, 2
  12. 3
  13. 0
  14. 2
  15. repeats code
  16. 2
  17. 1
  18. 1
  19. Hi, Aman
  20. 36
  21. 37
  22. Hi, Kabir
  23. 4
  24. 18
  25. 44
  26. 17
  27. 15
  28. Hi, Kabir
  29. 3
  30. 13
  31. 14
  32. 31
  33. Hi, Aman
  34. 17
  35. 2
  36. 20
  37. Hi, Arjun
  38. 1
  39. 79
  40. Hi, Kabir

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