Answer:
[tex]\large\boxed{\sqrt{0.15}\approx0.39\approx0.4}[/tex]
Step-by-step explanation:
[tex]\sqrt{a}=b\iff b^2=a\ \text{for}\ a\geq0\ \wedge\ b\geq0.\\-------------------\\\\0.4^2=0.16>0.15\\0.3^2=0.09<0.15\\0.39^2=0.1521>0.15\\0.38^2=0.1444<0.15[/tex]