Exercises 7.8 Multiple Choice Questions

1.

Q-1: Which line of code correctly adds an item to the fruits dictionary with a key of ‘grapes’ and a value of 15?

fruits = {'apples': 1, 'bananas': 4, 'pears': 17, 'oranges': 14}

fruits[’grapes’]
Try again! This does not add a value.
fruits[’grapes’] = 15
Correct! This line adds ’grapes’ as a key with a value of 15.
insert ’grapes’ in fruits
Try again! This is not correct Python.
fruits[15] = ’grapes’
Try again! This sets the key to 15 and the value to ’grapes’.

2.

Q-2: What does the following code print?

names = {'Janice': 5, 'Emily': 3, 'John': 7, 'Eleanor': 2}
list_o_names = []
for name in names:
    if names[name] > 5:
        list_o_names.append(name)
print(list_o_names)

[’Janice’, ’John’]
Try again! This would be true if it was greater than or equal 5.
[’Janice’, ’Emily’, ’Eleanor’]
Try again! This only adds items with a value greater than 5.
[’John’]
Correct! John is the only key that has a value greater than 5.
[’Janice’, ’Emily’, ’John’, ’Eleanor’]
Try again! This only adds items with a value greater than 5.

3.

Q-3: What does the following code print?

names = {'Janice': 5, 'Emily': 3, 'John': 7, 'Eleanor': 2}
list_o_names = []

names['Emily'] += 10
names['Erik'] = 22

for name in names:
    if names[name] > 5:
        list_o_names.append(name)
print(list_o_names)

[’Emily’, ’John’, ’Erik’]
Correct! Erik is initialized to 22, and Emily is updated to 13. Therefore, these two entries are added to the list found in the previous question.
[’Janice’, ’Emily’, ’John’]
Try again! Erik is set to 22, so it should be added.
[’Janice’, ’John’, ’Erik’]
Try again! Emily is set to 13, so it should be added.
[’Janice’, ’Emily’, ’John’, ’Eleanor’]
Try again! This will not add Eleanor since the value is 2, and this will not add Janice since the value is 5.

4.

Q-4: What is the value of counter after the code is run?

phrase = "Cheese in Philadelphia is extraordinary according to Erik"

counter = 0
letters = {}
for word in phrase.split():
    for letter in word:
        letter = letter.lower()
        if letter not in letters.keys():
            letters[letter] = 0
        letters[letter] += 1
for key in letters.keys():
    if letters[key] > 2:
        counter += 1

5
Try again!
10
Try again!
9
Correct! There are 9 letters in phrase that appear more than two times.

5.

Q-5: Which line of code correctly gets the value of the key ‘apples’ if it exists and returns 0 if it does not?

fruits = {'bananas': 7, 'apples': 4, 'grapes': 19, 'pears': 4}

fruits.get(apples)
Try again! The key must be a string in this case.
fruits.get(’apples’, 0)
Correct! This correctly grabs the key as a string and also includes a default value in case the key is not present in the dictionary.
fruits.get(’apple’)
Try again! This will return None if the key does not exist.
fruits.get(apples, 0)
Try again! The key must be a string in this case.

6.

Q-6: What value is printed when this code runs?

word = 'brontosaurus'
diction = {}
for letter in word:
    if letter not in diction.keys():
        diction[letter] = 0
    diction[letter] += 1
print(diction.get('o', 0) + 4)

10
Try again!
4
Try again!
6
Correct! The get() method grabs the value 2 and then 4 gets added to it to get 6.
2
Try again! This would be true if it just printed the value for the key ’o’. However, 4 is added to it.

7.

Q-7: What order do the keys print in after the following code is run?

counts = {'annie' : 42, 'chuck' : 1, 'jan' : 100}
for key in counts:
    print(key)

jan, chuck, annie
The order is their order in the dictionary.
chuck, annie, jan
The order is their order in the dictionary.
annie, chuck, jan
Correct! The order is their order in the dictionary.
jan, annie, chuck
The order is their order in the dictionary.

8.

Q-8: What order do the keys print in after the following code is run?

counts = {'annie' : 42, 'chuck' : 1, 'jan' : 100}
items = counts.items()
out = sorted(items, reverse = True)
for item in out:
    print(item[0])

jan, chuck, annie
Correct! This will sort by the keys in descending order.
chuck, annie, jan
This will sort by the keys in descending order.
annie, chuck, jan
This will sort by the keys in descending order.
jan, annie, chuck
This will sort by the keys in descending order.

9.

Q-9: What order do the keys print in after the following code is run?

counts = {'annie' : 42, 'chuck' : 1, 'jan' : 100}
items = counts.items()
out = sorted(items, key = lambda t: t[1])
for item in out:
    print(item[0])

jan, chuck, annie
This will sort by the values in ascending order.
chuck, annie, jan
Correct! This will sort by the values in ascending order.
annie, chuck, jan
This will sort by the values in ascending order.
jan, annie, chuck
This will sort by the values in ascending order.

10.

Q-10: What order do the keys print in after the following code is run?

counts = {'annie' : 42, 'chuck' : 1, 'jan' : 100}
items = counts.items()
sorted(items, key = lambda t: t[1])
for item in items:
    print(item[0])

jan, chuck, annie
This will print the keys in their current order since sorted returns a new list.
chuck, annie, jan
This will print the keys in their current order since sorted returns a new list.
annie, chuck, jan
Correct! This will print the keys in their current order since sorted returns a new list.
jan, annie, chuck
This will print the keys in their current order since sorted returns a new list.

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