3. Calculate standard deviation from the following data? Using short cut method and step deviation method? Calculate co-efficient of standard deviation.
X 0-5 5-10 10-15 15-20 20-25
frequency 2 5 10 6 2
Answers
Answer
31
Explanation:
The formula used for arithmetic mean of grouped data by step deviation method is, X=A+∑f∑fu×i
A= Assumed mean of the given data
∑ = Summation of the frequencies given in the grouped data
∑fu = Summation of the frequencies and deviation of a given mean data
u=i(x−A)
i= Class interval width
X = arithmetic mean
X=22.5+105172×5
=22.5+8.19
=30.69 ≈ 31
Answer:
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Class 7
>>Maths
>>Perimeter and Area
>>Perimeter and Area of a Circle
>>The area of circle is 25 picm^2. Find it
Question
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The area of circle is 25π cm
2
. Find its circumference.
Medium
Solution
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Let the radius of the circle be r.
The area of the circle is given as,
πr
2
r
2
r
=25π
=25
=5 cm
Hence, the circumference of circle will be,
2πr
=2×
7
22
×5
=
7
220
=31.428 cm
Hence, the circumference of the circle is equal to 31.428 cm.