Question 4: Who arrived last? Ibrahim arrived five minutes before Nze. Abu was late. Question 5: X is four times as great as another number. Another number is two less than twenty. Find X. Question 6:

• Ibrahim arrived five minutes before Nze. This means Nze arrived after Ibrahim.
• Abu was late. This implies Abu arrived after everyone else.

The order of arrival is Ibrahim, then Nze, then Abu.

The last person to arrive was Abu.
The answer is Abu.

The problem states that "another number" is two less than twenty.

The problem states that X is four times as great as the "another number".

The value of X is $\boxed{\text{72}}$.

The question states: "If the smallest of the following fruits were the most costly..."

The fruits are Orange, grapefruit, mango, guava, banana. Among these, guava is generally considered the smallest in size.

Since the smallest fruit is stated to be the most costly, and guava is the smallest fruit listed, you would have to pay the most for guava.
The answer is guava.