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The marks obtained by 10 pupils in an English text were 15,14,12,13,p,16,11,13,12 and 17. The sum of the squares of the marks, ∑x2 is 1,794.
(a) Calculate the: (i)value of p (ii) Standard deviation
(b) If each marks is increased by 3,write down the : (i)new mean (ii)new standard deviation.