Answer Happy

C) For a highway bridge, the results of the tensile strengths from a sample of a certain prime coat material at the age of 7 days are as shown in Table 2. Table 2 Results from the sample for the prime coat material Strength 260-290 290 320 320 - 350 350-380 380-410 410-440 440-470 (kN/m²) P Frequency 1 8 35 18 8 0 Construct a frequency table and clearly show your calculations for the mean tensile strength together with the range and standard deviation representing this sample. (10 Marks) ii) If the permissible tensile strength allowed in design is equal to the mean less 2.33 times the standard deviation indicate whether any of the sampled brittle prime coat test pieces fell below this strength. (4 Marks) iii) What is the probability that in a sample of 12, less than 2 results show a tensile strength below 320 kN/m²? (10 Marks)