Which country launches the world's first fully-fledged 5G mobile networks?

The average age of father and his son is 22 years. The ratio of their ages is 10 : 1 respectively. What is the age of the son?

A man drives his car 50 km towards an eastward direction. He turned right went for 30km, then he turned west and drive for 10 km. How far is he from the starting point?

A man starts walking from a point and walks 12 kms towards north. He turns 90⁰ left walks a distance and stopped. If the distance between initial point and final positions is 13 kms, how much distance he travelled after turning from the North?

Direction: In the following question, select the related letters from the given alternatives.
Cotton : White :: Coal : ?

A vessel contains 20 litres of acid. 4 is taken out of the vessel and replaced by the same quantity of water. Next 4 litres of the mixture are withdrawn, and again the vessel is filled with the same quantity of water. Then find the ratio of acid left in the vessel with the quantity of acid initially in the vessel is:

A vessel contains 60 litres of milk. 12 litres of milk taken out from it and replaced with water. Then again form mixture, 12 litres is taken out and replaced with water. The ratio of milk and water in the resultant mixture is :

If 8, X and 50 are in continued proportion, then the value of x is