Surface area of pyramid (1 Viewer)

[Jigmey]

Stuck on these questions for weeks!
My working out is 1/2 x 10 x sqrt120 + 1/2 x 10 x sqrt375 + 2 x 1/2 x 12 x sqrt256
I keep on getting 343.5968394 = 343.6 but the answer in the text book is 343.4

 

[StudyOnly]

SA = 1/2 x 10 x sqrt(375) + 1/2 x 10 x sqrt(119) + 2 x 1/2 x 16 x 12
= 343.3681442.....
= 343.4m^2