1901: The average height of 2 students in a class is 115 cm. Ten more students with an average height of 130 cm join them. Therefore, the average height of the group of students now becomes:
(a) 110 cm
(b) 120 cm
(c) 130 cm
(d) 140 cm
1902: Swamps are seen in the Siberian rivers because
(a) Freezing of the river near the mouth prevents water to flow to the sea
(b) Rivers are too narrow
(c) Rivers are heavily drained by the large network of canals
(d) Railway bridges built across the rivers obstruct the flow
1903: Acid rain is caused by the pollution of environment by
(a) carbon dioxide and nitrogen
(b) carbon monoxide and carbon dioxide
(c) ozone and carbon dioxide
(d) nitrous oxide and sulphur dioxide
1904: If 15 pumps of equal capacity can fill a tank in 7 days, then how many extra pumps will be required to fill the tank in 5 days?
(a) 6
(b) 7
(c) 14
(d) 21
1905: Sodium vapour lamps are preferred to incandescent lamps because of:
(a) Higher efficiency
(b) Higher tolerance in voltage fluctuations
(c) Easy installation
(d) Higher intensity of illumination