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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 193 · 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 scores = [15, 10, 10, 2];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  2. 2.🔁 What number does this code show?
    let marks = [34, 61, 95];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Meera (d) Hi, Riya
  4. 4.🔁 What number does this code show?
    let scores = [3, 3, 7];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  5. 5.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 6 (c) 1 (d) 5
  6. 6.🔁 What number does this code show?
    let steps = [10, 1, 19, 10, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let scores = [5, 11, 10, 10, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya
  9. 9.🔁 What number does this code show?
    let marks = [15, 2, 18, 8, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  10. 10.🔁 What number does this code show?
    let steps = [41, 75, 17, 55, 32];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What does a loop do? (a) draws icons (b) deletes code (c) saves photos (d) repeats code
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya (d) Hi, Aman
  13. 13.🔁 What number does this code show?
    let steps = [4, 12, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  14. 14.🔁 What number does this code show?
    let steps = [18, 13, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  15. 15.🔁 What number does this code show?
    let steps = [1, 1, 4, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let scores = [17, 11, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  17. 17.🔁 list.length tells you ___. (a) how many items it has (b) the last item (c) the first item (d) the biggest item
  18. 18.🔁 What number does this code show?
    let scores = [75, 43, 14, 20];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let marks = [9, 5, 16];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let scores = [59, 13, 57, 93];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let steps = [1, 11, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let runs = [1, 10, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Riya (d) Hi, Kabir
  24. 24.🔁 What number does this code show?
    let scores = [25, 86, 40, 20];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya (d) Hi, Zoya
  26. 26.🔁 What number does this code show?
    let runs = [58, 37, 61];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Zoya", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Zoya
  28. 28.🔁 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
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya
  30. 30.🔁 What number does this code show?
    let scores = [20, 17, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  31. 31.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 1, 2, 3
  32. 32.🔁 What number does this code show?
    let runs = [7, 11, 2, 19, 14];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let scores = [12, 12, 2, 10, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let steps = [95, 52, 19];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let scores = [8, 17, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let scores = [15, 3, 19];
    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", "Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Aman (d) Hi, Riya
  38. 38.🔁 What number does this code show?
    let steps = [10, 1, 11];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let marks = [55, 15, 45, 10, 88];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let steps = [12, 17, 1, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);

Answer key

  1. 15
  2. 1
  3. Hi, Aman
  4. 7
  5. 5
  6. 53
  7. 56
  8. Hi, Meera
  9. 55
  10. 2
  11. repeats code
  12. Hi, Riya
  13. 17
  14. 18
  15. 23
  16. 17
  17. how many items it has
  18. 1
  19. 30
  20. 3
  21. 20
  22. 10
  23. Hi, Zoya
  24. 2
  25. Hi, Arjun
  26. 0
  27. Hi, Meera
  28. less code to write
  29. Hi, Arjun
  30. 42
  31. 0, 1, 2
  32. 19
  33. 45
  34. 1
  35. 36
  36. 19
  37. Hi, Kabir
  38. 22
  39. 3
  40. 31

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