A 3.5hp outboard will give you 8mph tops, which would be a normal walk to a slow jog.
First, it needs to be mounted on the boat. And the boat determines how fast the attached motor will go. If the boat is wood, then it will likely float deeper in the water, and not be particularly fast. If the boat is a smaller fiberglas one, then the motor and boat will go faster. Based on much boating experience, I would say that most boats could go 30 to 35 mph with the 40hp Merc.
The Motor will do 35-40mph
150MLP
E=mc2
70
Depends on how fast the boat is traveling. On a boat traveling at 30 mph it will take 30 minutes.
I have a 2.7m Inflatable boat and have a 2.5hp Marriner engine the engine will allow the boat to cruise at around 8knots and that is with 3 of us in the boat.
Speed is dependant on a number of factors. Most importantly the size, type and weight of the boat that it is on and the number of people on board. A 50 HP outboard will push a small aluminum fishing boat a lot fast than it will a 20 ft fiberglass boat. I have a 50 HP 2 stroke that will push a 16 foot aluminum boat 35 MPH.
It depends on the boat you have it on. You might go 60 mph if you put the motor on a high-performance center-console fishing boat. You might also go 5 mph if you put it on a tugboat that's pulling logs down the river.
About 10 to 12 on plane
It really depends on how big your boat is and how fast you want to go typically you want to go 20-25 while tubing so get a big enough motor to push your boat with a tube 20-25 mph
Impossible to answer this question without knowing the coefficient of drag of the boat it is attached to.