## Questions d'entretien

Entretien pour Firmware Engineer

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# Puzzles 1: You have rope that take 60 min to burn. Speed of burning is not uniform. Example: it doesn't take 30 min to burn half Using two ropes, how would you get 45 min? Answer: First Rope. Burn both ends at same time Second Rope: Burn only one side. when First rope is totally burn, it's been 30 min, now burn the rest of second rope both ends. Which should take additional 15 min. 30 + 15 = 45 min. Puzzle 2: There is a guy in a boat holding a rope that's tight to a Top of pole in the shore. He keep pulling the rope until he reach the shore. What is the speed relationship between amount of rope he pulls, vs horizonal speed? Which speed is higher? Answer: Horizonal speed is faster than the amount of rope he pulls. (Horizonal distance he travel is higher than amount of rope he pulls, by triangle theory where sum of two sides must be greater than 3rd side) Puzzle 3: in Analog Clock, It's exacly 3:00 Clock. What time would the Hour hand, and Min hand would overlap each other?

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## Réponses aux questions d'entretien

4 réponse(s)

9

The analog and min hand overlap once each hour so the next overlap after 3:00 would be 3:16 and some change. Sanity check: 16 minutes should be between the 3:00 and 4:00 on the clock, which is true. Math: Hour hand gets an equation like 3 + (1/60)*minutes, since the hour hand starts at 3 and every minute it increases by 1/60th of an hour. The minute hand gets 12*(1/60) * minutes since in 60 minutes it goes around the 12 hours of the clock. So 3+(1/60)x = (12/60)x gives you 180/11 or about 16.

Gob le

1

1) hour = min / 12 deg 2) min = hour + hour(initial) = hour + 90 deg 1=>2 and solving gives 98.18 deg. Converting back into time format gives 3:16:22.

Simeon le

0

you should keep the same units: Hour hand: starts at 15 min so 15 min + 5 min/hr*t Min hand: 60 min/hr 15 min + 5 min/hr * t = 60 min/hr 15 min = 55 min/hr * t 15/55 = .2727 hr .2727 hr * 60 min/hr = 16.3636 min = 16 min 21.8182 sec

Bill le

4

for Puzzle 3: It's 6:30

widlar_woody le

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