Pick up the incorrect statemnt from the following. For performing compressive strength test of cement

• cement and standard sand mortar are used in the ratio of 1 : 3
• water is added at the rate of + 3.0 percentage of water where P is the percentage of water for standard consistency
• A cube mould of 10 cm x 10 cm x 10 cm is used
• The perpared moulds are kept in a atmosphere of 50% relative humidity
• The temperature of water in the submerged tank for curing moulds, should be 27° ± 2°C.