How many overs in a World Cup cricket match?

Question

According to time period between two world cup there should be 4 years gap but last world cup played in 1996(Asia), so why is that happen?

Answer 1

50 Overs

In 1975 the first Cricket World Cup was contested in England as a series of one-day matches of 60 overs per side. It was held outside England, in India and Pakistan, for the first time in 1987. The 1987 contest also saw the number of overs per side reduced to 50.