coding-test.rb

# We save a series of custom events when a student takes a quiz. These events
# give us interesting insights into quiz-taking behavior.
#
# We want to write code that uses these events to answer questions
# about a particular quiz attempt.
#
## The Events
# We store the events in a series of records stored as JSON. There are
# six different types of events:
#  - `start_quiz`:      The student started taking the quiz
#  - `view_question`:   The student viewed a question in the browser
#  - `answer_question`: The student answered a question
#  - `page_blurred`:    The student exited the browser window
#  - `page_focused`:    The student reentered the browser window
#  - `submit_quiz`:     The student submitted the quiz
# The question: What was the overall average time for all the question to be finally answered? "MM:SS"
# Example statement we want to make at the end: "On average, it took this student 2 minutes to answer a question"


input_data = <<END
[
  { "id": 1,  "event_type": "start_quiz",      "created_at": "2021-03-02T13:35:40-07:00", "event_data": {} },
  { "id": 2,  "event_type": "view_question",   "created_at": "2021-03-02T13:35:42-07:00", "event_data": { "question_id": 1 } },
  { "id": 3,  "event_type": "answer_question", "created_at": "2021-03-02T13:36:12-07:00", "event_data": { "question_id": 1, "answer": { "option_id": "584" } } },
  { "id": 4,  "event_type": "view_question",   "created_at": "2021-03-02T13:36:14-07:00", "event_data": { "question_id": 2 } },
  { "id": 5,  "event_type": "answer_question", "created_at": "2021-03-02T13:37:24-07:00", "event_data": { "question_id": 2, "answer": { "option_id": "824" } } },
  { "id": 6,  "event_type": "view_question",   "created_at": "2021-03-02T13:37:29-07:00", "event_data": { "question_id": 3 } },
  { "id": 7,  "event_type": "view_question",   "created_at": "2021-03-02T13:37:30-07:00", "event_data": { "question_id": 4 } },
  { "id": 8,  "event_type": "view_question",   "created_at": "2021-03-02T13:37:31-07:00", "event_data": { "question_id": 5 } },
  { "id": 9,  "event_type": "view_question",   "created_at": "2021-03-02T13:37:34-07:00", "event_data": { "question_id": 4 } },
  { "id": 10, "event_type": "view_question",   "created_at": "2021-03-02T13:37:35-07:00", "event_data": { "question_id": 3 } },
  { "id": 11, "event_type": "answer_question", "created_at": "2021-03-02T13:40:55-07:00", "event_data": { "question_id": 3, "answer": { "option_id": "427" } } },
  { "id": 12, "event_type": "view_question",   "created_at": "2021-03-02T13:40:56-07:00", "event_data": { "question_id": 4 } },
  { "id": 13, "event_type": "answer_question", "created_at": "2021-03-02T13:42:55-07:00", "event_data": { "question_id": 4, "answer": { "option_id": "602" } } }, 
  { "id": 14, "event_type": "view_question",   "created_at": "2021-03-02T13:42:59-07:00", "event_data": { "question_id": 4 } },
  { "id": 15, "event_type": "view_question",   "created_at": "2021-03-02T13:43:00-07:00", "event_data": { "question_id": 3 } },
  { "id": 16, "event_type": "page_blurred",    "created_at": "2021-03-02T13:43:08-07:00", "event_data": {} },
  { "id": 17, "event_type": "page_focused",    "created_at": "2021-03-02T13:47:29-07:00", "event_data": {} },
  { "id": 18, "event_type": "answer_question", "created_at": "2021-03-02T13:47:33-07:00", "event_data": { "question_id": 2, "answer": { "option_id": "276" } } },
  { "id": 19, "event_type": "view_question",   "created_at": "2021-03-02T13:47:36-07:00", "event_data": { "question_id": 3 } },
  { "id": 20, "event_type": "view_question",   "created_at": "2021-03-02T13:47:37-07:00", "event_data": { "question_id": 4 } },
  { "id": 21, "event_type": "view_question",   "created_at": "2021-03-02T13:47:38-07:00", "event_data": { "question_id": 5 } },
  { "id": 22, "event_type": "answer_question", "created_at": "2021-03-02T13:50:24-07:00", "event_data": { "question_id": 5, "answer": { "option_id": "486" } } },
  { "id": 23, "event_type": "view_question",   "created_at": "2021-03-02T13:50:26-07:00", "event_data": { "question_id": 4 } },
  { "id": 24, "event_type": "page_blurred",    "created_at": "2021-03-02T13:50:30-07:00", "event_data": {} },
  { "id": 25, "event_type": "page_focused",    "created_at": "2021-03-02T13:56:08-07:00", "event_data": {} },
  { "id": 26, "event_type": "answer_question", "created_at": "2021-03-02T13:56:17-07:00", "event_data": { "question_id": 4, "answer": { "option_id": "343" } } },
  { "id": 27, "event_type": "view_question",   "created_at": "2021-03-02T13:56:20-07:00", "event_data": { "question_id": 5 } },
  { "id": 28, "event_type": "submit_quiz",     "created_at": "2021-03-02T13:56:25-07:00", "event_data": {} }
]
END