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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 289 · 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.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 6 (d) 5
  2. 2.🔁 What number does this code show?
    let steps = [73, 10, 81];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it uses more lines (c) it hides them (d) it is slower
  4. 4.🔁 What number does this code show?
    let scores = [11, 6, 5, 20, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  5. 5.🔁 What number does this code show?
    let steps = [82, 79, 93, 28];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What does a loop do? (a) saves photos (b) deletes code (c) repeats code (d) draws icons
  7. 7.🔁 What number does this code show?
    let marks = [5, 12, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let scores = [20, 15, 20, 16];
    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 = [3, 19, 5, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Meera
  11. 11.🔁 What number does this code show?
    let scores = [6, 19, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  12. 12.🔁 What number does this code show?
    let steps = [56, 10, 56, 97, 33];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  13. 13.🔁 What number does this code show?
    let marks = [4, 16, 8, 13];
    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 runs = [36, 65, 16, 52, 28];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let steps = [7, 8, 3, 2, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Zoya
  17. 17.🔁 What number does this code show?
    let marks = [3, 11, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let marks = [11, 9, 14, 9];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Arjun
  20. 20.🔁 What number does this code show?
    let marks = [27, 10, 37, 12, 52];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let marks = [79, 30, 20];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Arjun", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
  23. 23.🔁 What number does this code show?
    let steps = [2, 18, 16];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  24. 24.🔁 What number does this code show?
    let runs = [14, 8, 19];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let steps = [20, 10, 16, 3, 5];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  26. 26.🔁 What number does this code show?
    let runs = [12, 6, 14];
    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 = [60, 57, 97, 80, 47];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Kabir (d) Hi, Arjun
  29. 29.🔁 What number does this code show?
    let scores = [2, 18, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  30. 30.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Aman (d) Hi, Zoya
  31. 31.🔁 What number does this code show?
    let runs = [7, 2, 18];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Zoya (d) Hi, Arjun
  33. 33.🔁 What number does this code show?
    let scores = [18, 15, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let runs = [2, 6, 16, 3, 10];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Arjun (d) Hi, Kabir
  36. 36.🔁 What number does this code show?
    let scores = [2, 6, 6, 4, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Aman
  38. 38.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Zoya
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Meera", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Arjun (d) Hi, Kabir
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Meera

Answer key

  1. 5
  2. 2
  3. less code to write
  4. 20
  5. 3
  6. repeats code
  7. 19
  8. 71
  9. 44
  10. Hi, Arjun
  11. 19
  12. 3
  13. 16
  14. 0
  15. 26
  16. Hi, Aman
  17. 16
  18. 43
  19. Hi, Kabir
  20. 0
  21. 1
  22. Hi, Riya
  23. 18
  24. 19
  25. 20
  26. 14
  27. 5
  28. Hi, Kabir
  29. 18
  30. Hi, Aman
  31. 18
  32. Hi, Riya
  33. 19
  34. 16
  35. Hi, Kabir
  36. 6
  37. Hi, Riya
  38. Hi, Kabir
  39. Hi, Kabir
  40. Hi, Meera

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