Recipe requires 15mins to cook. you have 7 mins hourglass and a 11 mins hourglass with you. how will you measure 15 mins using them?
Choose the correct choice from the following answers
A) 15 mins  B) 12 mins  C) 13 mins  D) 17 mins  E) 20 mins

Rationale: correct answer : a put up both hour glasses . time starts when 7 min hourglass turns empty . and 11 min hourglass will run for 4 min . now flip 11 min hour glass upside down as soon as it runs empty . it will be empty in another 11 mins . and time is up . so 4 + 11 = 15 mins
Answer: A