MHB Mean & Std Dev for Norm Dist. Exam Marks - 450 Stud.

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To find the mean and standard deviation of exam marks for 450 students with a normal distribution, the number of first-class students (25) and failed students (90) are key data points. The first-class threshold is set at 60% or more, while the failure threshold is below 30%. This distribution indicates that 335 students scored between 30% and 60%. Calculating the mean and standard deviation requires additional statistical methods or formulas based on these figures. Providing initial calculations or attempts would facilitate more targeted assistance.
wajeehayas
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Assuming that the number of marks scored by a candidate is normally distributed, find the mean and the standard deviation, if the number of first class students(60% or more marks) is 25, the number of failed students(less than 30%marks) is 90 and the total number of candidates appearing for the examination is 450.
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Hello wajeehayas and welcome to MHB! :D

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