29. The grade of reinforced concrete to be used in sea water or structures exposed to sea water should be
30. The maximum compressive strength on 15 cm cubes of M 20 grade concrete at 7 days, should be a minimum of
31. The minimum compressive strength on 15 cm cubes of M 30 grade concrete at 7 days, should be a minimum of
32. The ratio of minimum compressive strength on 15 cm cubes prepared with the concrete of M 20 grade and M 40 grade, at 7 days should be at least
34. If A is the deviation of the individual test strength from the average of n samples, the standard deviation of concrete of the given grade is
35. The concrete is deemed not to comply with the strength requirements if the strength is less than the greater of
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