GMAT Quantitative Reasoning Practice Test 2

Question : 8 of 100

Marks: +1, -0

A snail, climbing a 20 feet high wall, climbs up 4 feet on the first day but slides down 2 feet on the second. It climbs 4 feet on the third day and slides down again 2 feet on the fourth day. If this pattern continues, how many days will it take the snail to reach the top of the wall?