How long does a radar signal take to travel from earth to venus and back when venus is brightest?

Given data:

Velocity of radar signal, v = Velocity of light = 3 x 10^8 m/s

Greatest distance between Venus and Earth d1 = 0.47 AU = 0.47 AU (a. 5 x 10^11 m / 1 AU) = 7.1x10^10 m

Closest distance between Venus and Earth, d2 = 0.28 AU = 0.28 AU (1.5 x 10^11 m / 1 AU) = 4.2 x 10^10 m

The time take by radar signal to travel from Earth to Venus and back when Venus is brightest is calculated as

T1 = 2d1/v = 2 (7. a x 10^10 m / 3 x10^8 m/s) = 473 s

The time taken by radar signal to travel from Earth to Venus and back when Venus is closest is calculated as

T2 = 2d1/v = 2 (4.2 x 10^10 m) / 3 x 10^8 m/s = 280 s