Here, IL : IP = 4 : 5;
IF = 150,
IP = ?
\(\therefore \frac{I_L}{I_P} = \frac 45\)
\(\therefore{I_L} = \frac 45{I_P}\)
Now, \(I_F = \sqrt{I_L \times I_P}\)
\(150 = \sqrt{\frac 45 I_P \times I_P}\)
\( (150)^2 = {\frac 45 {I_P}^2}\)
\(\frac{22500\times 5}{4} = {\frac 45 {I_P}^2}\)
\({I_P}^2 = 28125\)
\(\therefore {I_P}= 167.71\)