When a laboratory test was carried out on a pump, it was found that for a pump total head of 36m at a discharge of 0.05m³/s cavitation began when the sum of the static pressure plus velocity head at the inlet was reduced to 3.5m. the atmospheric was 760mmHg and the vapor pressure of water was 1.8kpa. 

If the pump is to operate at a location where atmospheric pressure is reduced to 620 mmHg and the vapor pressure of water is 830 pa, what is the value of the cavitation parameter when the pump develops the same total head and discharges? 

Is it necessary to reduce the height of the pump above the supply, and if so by how much?