Marks of Raj, Ram, Rohan, Ahmed, Akash, Akram, Mohit, Raju, Mohan, Ricky and Rahul who are students

M4maths Previous Puzzles

26 Jul 2018 Standard Deviation

Marks of Raj, Ram, Rohan, Ahmed, Akash, Akram, Mohit, Raju, Mohan, Ricky and Rahul who are students of a coaching institute are: 73 64 74 81 77 71 75 78 59 72 and 74 respectively.

What is the population standard deviation of their marks?

OPtion

1) 5.89
2) 5.39
3) 5.59
4) 5.99
5) 5.91
6) 6.25
7) 5.81
8) 5.96
9) 6.19
10)None of these

Solution

Mean of 11 marks = 798/11 = 72.54
Sum of squared difference from mean for each number = (73-72.6)^2 + (64-72.6)^2 + ......+ (74-72.6)^2 = 390.76

Average of Squared difference (Variance) = 390.76/11 = 35.52
Population Standard Deviation = Square root of variance = 35.52^1/2 = ~5.96

Option 8)

Correct Option: 8 Best Solution (5)

G.S.Kantharao   6 years AGO

S.D=√(Sigma(X-M)^2/N)=5.96
Hence my option is 8👈

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Varun   6 years AGO

Total numbers = 11
It is calculated as square root of[(1/n)*summation 1 to N(xi-mean)square]

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SAYAN CHATTERJEE   6 years AGO

Avg. is (73+64+74+81+77+71+75+78+59+72+74)/11= 72.545.
Now, standard deviation is √((Xn-avg)^2/n)
= 5.96.
Option 8.

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akhila   6 years AGO

Mean of those marks=72.5454545
Substituting all the values in standard deviation formula answer is 5.9566~=9.6

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madhuri banda    6 years AGO

average of given numbers = (total sum)/11
Mean = 72.545

Subtract Mean from each point and suare the results

Take Mean of the Squared difference value
This gives the deviation
As we need Standard deviation

take root of the SQUARED DIFFERENCE MEAN
ans = 5.96

option 8)

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