Vault Guide to Private Equity and Hedge Fund InterviewsBrainteasers10.Four investment bankers need to cross a bridge at night to get to ameeting. They have only one flashlight and 17 minutes left to get to themeeting. The bridge must be crossed with the flashlight and can onlysupport two bankers at a time. The analyst can cross in one minute, theassociate can cross in two minutes, the VP can cross in five minutes andthe MD takes 10 minutes to cross. How can they all make it to themeeting in time?First, the analyst takes the flashlight and crosses the bridge with the associate.This takes two minutes. The analyst then returns across the bridge with theflashlight, taking one more minute (three minutes passed so far). The analystgives the flashlight to the VP and the VP and MD cross together, taking 10minutes (13 minutes passed so far). The VP gives the flashlight to the associate,who re-crosses the bridge taking two minutes (15 minutes passed so far). Theanalyst and associate now cross the bridge together taking two more minutes.Now, all are across the bridge for the meeting in exactly 17 minutes.11.A lily in a pond doubles every minute. After an hour, the lily fills the entirepond. When is it one-eighth full?Work backwards. At 59 minutes, it is half full. At 58 minutes, it’s one-fourth full.Thus, after 57 minutes, it is one-eighth full.12.What is larger, 3^4 or 4^3?3"4. In most combinations, the lower number " higher number is higher thanvice versa because the higher exponential has a powerful multiplier effect.However, 2"3 is higher than 3"2, but you can solve that particular anomaly inyour head.