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1.What does the `collect!` method do in Ruby Enumerables?

Returns a new array with modified elements.

Modifies the original array by applying a block to each element.

Sorts the elements in ascending order.

Counts the occurrences of a specific element.

2.How can you find the index of the last occurrence of a specific element in an Enumerable?

last_index

rindex

find_last

index_last

3.What is the purpose of the `reduce` method in Ruby Enumerables?

Counts the occurrences of a specific element.

Combines all elements into a single value by applying a binary operation.

Transforms each element using a block.

Filters elements based on a given condition.

4.How do you filter elements in an Enumerable based on a given condition and return a new array?

include

filter

choose

select

5.What does the `any?` method check in Enumerables?

If the collection is empty.

If all elements in the collection satisfy a given condition.

If none of the elements in the collection satisfy a given condition.

If any element in the collection satisfies a given condition.

6.How can you find the first n elements in an Enumerable that satisfy a given condition?

find_first

select_first

first_n

take_while

7.What is the output of the following code?

arr = [1, 2, 3, 4, 5]
result = arr.map { |x| x * 2 }
puts result.join(',')

1,2,3,4,5

2,4,6,8,10

1,4,9,16,25

2,3,4,5,6

8.How can you find the even numbers in an Enumerable?

even?

filter{ |e| e.even? }

select(&:even?)

even_numbers

9.What is the purpose of the `drop_while` method in Enumerables?

Counts the occurrences of a specific element.

Drops elements from the end of the collection until the block condition is true.

Transforms each element using a block.

Drops elements from the beginning of the collection until the block condition is false.

10.How do you check if all elements in an Enumerable are of a certain class?

all?{|e| e.is_a?(ClassName)}

every?{|e| e.is_a?(ClassName)}

type?{|e| e.is_a?(ClassName)}

is_a?{|e| e.is_a?(ClassName)}

11.How can you find the sum of the squares of elements in an Enumerable?

map{ |e| e**2}.sum

collect{ |e| e**2}.sum

sum{ |e| e**2}

squares.sum

12.What does the `slice_after` method do in Ruby Enumerables?

Returns the last element in the collection.

Groups consecutive elements based on a given block.

Slices the collection after a given element.

Shuffles the elements randomly.

13.How do you check if an element is present in an Enumerable using a custom condition?

any?{|e| custom_condition(e)}

exists?{ |e| custom_condition(e)}

contains?{ |e| custom_condition(e)}

has?{ |e| custom_condition(e)}

14.What is the purpose of the `zip` method in Ruby Enumerables?

Unzips an array of arrays into two separate Enumerables.

Combines corresponding elements from two Enumerables into an array of arrays.

Zips elements in random order.

Creates a zip file containing the Enumerables.

15.How can you find the average value of elements in an Enumerable?

sum / size

average

avg

mean

16.What does the `each_with_index` method do?

Iterates over each element along with its index.

Counts the number of elements in the collection.

Transforms each element using a block.

Selects elements based on a given condition.

17.How can you remove nil values from an Enumerable?

compact

remove_nil

exclude_nil

reject_nil

18.What is the result of the following code?

arr = [1, 2, 3, 4, 5]
result = arr.reduce(0) { |sum, x| sum + x }
puts result

15

10

5

0

19.How does the `map` method differ from the `each` method in Ruby Enumerables?

Filters elements based on a given condition.

Iterates over each element without modifying the original array.

Counts the number of elements in the collection.

Applies a block to each element and returns a new array with the results.

20.What does the `chunk` method do in Ruby Enumerables?

Returns the last element in the collection.

Splits the collection into two equal parts.

Groups consecutive elements based on a given block.

Counts the occurrences of a specific element.

Enumerables IV