The height of the object : 600 mm
Given
d object=360 mm(object distance)
d image=90 mm(image distance)
Required
h object
Solution
focal length = f :
[tex]\tt \dfrac{1}{f}=\dfrac{1}{d_o}+\dfrac{1}{d_i}\\\\\dfrac{1}{f}=\dfrac{1}{360}+\dfrac{1}{90}\rightarrow f=72~mm[/tex]
The magnification :
[tex]\tt M=\dfrac{d_i}{d_o}=\dfrac{90}{360}=0.25[/tex]
[tex]\tt M=\dfrac{h_i}{h_o}\\\\0.25=\dfrac{150}{h_o}\rightarrow h_o=600~mm[/tex]