It is thought that the Brinell hardness of some ductile iron has an average of 17'0. An engineer examines 38 samples and finds an average value for the Brinell hardness to be 163, with a standard deviation of 10. At 5% level of significance, is there enough evidence to suggest that the actual hardness is less than it was thought? a] State the type of distribution {type 2 or t] [1 mark] b] State the type of test (type: left tail, or right tail, or two tail} [1 mark] c] State the critical value {values}. If there are 2 values, type both separated by comma, no spaces. Include the sign in front of each value. [2 marks] d} Calculate the test statistic, rounded to 3 decimal places. [2 marks] e} Make a decision {T ype: Enough evidence to support the datm, or Not enough evidence to support the ctatm}. Do not use bold or italics. [2 marks]