The ratio of starting torque to full load torque in a 3-phase squirrel cage induction motor can be determined using the concept of slip and the relationship between torque and current.

1. Slip:
The slip of an induction motor is defined as the difference between the synchronous speed and the actual rotor speed, divided by the synchronous speed. It is denoted by the symbol 's' and is given by the equation:
s = (Ns - Nr) / Ns

Where:
s = Slip
Ns = Synchronous speed of the motor
Nr = Rotor speed of the motor

2. Full Load Slip:
The full load slip of the motor is the slip at full load condition, where the motor is operating at its rated torque and speed. It is denoted by 'sFL' and is given by the equation:
sFL = (Ns - NrFL) / Ns

Where:
sFL = Full load slip
NrFL = Rotor speed at full load condition

3. Starting Current:
The starting current of an induction motor is typically higher than the rated current. In this case, it is given that the starting current is 5 times the rated current. Let's denote the starting current as 'Istart' and the rated current as 'Irated'.

4. Starting Torque:
The starting torque of an induction motor is directly proportional to the square of the starting current. Therefore, the starting torque can be expressed as:
Tstart = Kt * Istart^2

Where:
Tstart = Starting torque
Kt = Proportionality constant

5. Full Load Torque:
The full load torque of an induction motor is directly proportional to the square of the rated current. Therefore, the full load torque can be expressed as:
TFL = Kt * Irated^2

Where:
TFL = Full load torque

6. Ratio of Starting Torque to Full Load Torque:
To find the ratio of starting torque to full load torque, we can divide the equations for starting torque and full load torque:
Tstart / TFL = (Kt * Istart^2) / (Kt * Irated^2)
Tstart / TFL = (Istart / Irated)^2

7. Calculation:
Given that the starting current is 5 times the rated current, we can substitute this value into the equation:
Tstart / TFL = (5 * Irated / Irated)^2
Tstart / TFL = 25

Therefore, the ratio of starting torque to full load torque is 25.

The correct answer is not between 1.20 and 1.30. It seems there might be an error or misunderstanding in the question.