Answer
The solenoid should have $2.2\times 10^4$ turns.
Work Step by Step
We can find the required number of turns $N$ in the solenoid:
$B = \frac{\mu~N~I}{L}$
$N = \frac{B~L}{\mu~I}$
$N = \frac{(1.5~T)(1.5~m)}{(4\pi \times 10^{-7}~T~m/A)(80~A)}$
$N = 2.2\times 10^4$
The solenoid should have $2.2\times 10^4$ turns.
