Current-limiting resistor and nearest E24.
R = 150 Ω E24 ≈ 150 Ω P ≈ 0.0600 W ΔV = 3.000 V
Yes.
No.
Solve V, I, R, P from any two values.
Vin, R1, R2 → Vout; solve any missing value.
Value + prefix ↔ base SI (yotta…yocto).
GPA from letter grades on a 4.0 scale.