Oliver was drawing and replacing balls out of a bag. He first drew 3 balls, replaced 2 of them, drew out 4 more balls and replaced 1. How many balls did he have left in his hand?

Answer 1

After drawing 3 balls, he replaced 2 of them, so he still has 1 ball in his hand.
Then he drew out 4 more balls and replaced 1, so he still has 4 balls in his hand.
Therefore, Oliver has a total of 1 + 4 = 5 balls left in his hand.