πŸ“’ Too many exams? Don’t know which one suits you best? Book Your Free Expert πŸ‘‰ call Now!


    Question

    The marks (out of 50) of 5 students are: 10, 14, 18, x,

    26. The mean is 18. Find x and the standard deviation.
    A 7√3 Correct Answer Incorrect Answer
    B 3√2 Correct Answer Incorrect Answer
    C 4√2 Correct Answer Incorrect Answer
    D 2√2 Correct Answer Incorrect Answer

    Solution

    Mean = 18 β‡’ total sum = 5 Γ— 18 = 90 Known sum = 10 + 14 + 18 + 26 = 68 So x = 90 βˆ’ 68 = 22 Data: 10, 14, 18, 22, 26; mean = 18 Deviations from mean: 10 βˆ’ 18 = βˆ’8 14 βˆ’ 18 = βˆ’4 18 βˆ’ 18 = 0 22 βˆ’ 18 = 4 26 βˆ’ 18 = 8 Squares: 64, 16, 0, 16, 64 Sum of squares = 160 Standard deviation (population) = √(Ξ£(dΒ²)/n) = √(160/5) = √32 = 4√2.

    Practice Next
    ask-question