Answer:3.6
Step-by-step explanation:
Given
Architect decide to double the width
length increases by 50 percent
height increases by 20 percent
Let L,B,H be length,height and width of rectangular room
L'=1.5L
B'=2B
H'=1.2H
therefore new volume V'=L'\times B'\times H'

V'=3.6LBH
new volume is 3.6 times the original