Qus : 3
Jamia Millia Islamia PYQ
3
The mean of 100 observations is 50 and their standard deviation is 5.
The sum of squares of all observations is —
1
50,000 2
2,50,000 3
2,52,500 4
2,55,000 Go to Discussion
Jamia Millia Islamia Previous Year PYQ
Jamia Millia Islamia JAMIA MILLIA ISLAMIA MCA 2023 PYQ
Solution Let $\bar{x} = 50$, $\sigma = 5$, and $n = 100.$
We know,
$\sigma^2 = \dfrac{\sum x^2}{n} - \bar{x}^2$
$\Rightarrow \sum x^2 = n(\sigma^2 + \bar{x}^2)$
$= 100(5^2 + 50^2) = 100(25 + 2500) = 100 \times 2525 = 2,52,500.$
Qus : 4
Jamia Millia Islamia PYQ
2
The mean and standard deviation of marks obtained by 50 students of a cl ass i n
three subjects physics, mathematics and chemistry are as follows:
Which of the subjects show the highest and lowest variabilities respectively?
1
Mathematics, Physics
2
Chemistry, Mathematics 3
Mathematics, Chemistry 4
Chemistry, Physics Go to Discussion
Jamia Millia Islamia Previous Year PYQ
Jamia Millia Islamia JAMIA MILLIA ISLAMIA MCA 2020 PYQ
Solution Compare variability via coefficient of variation (CV) = SD / Mean.
Math: $12/42 \approx 0.286$
Physics: $15/32 \approx 0.469$
Chemistry: $20/40.9 \approx 0.489$
Highest CV → Chemistry; Lowest CV → Mathematics.
$\boxed{\text{Answer: (B) Chemistry, Mathematics}}$
Qus : 10
Jamia Millia Islamia PYQ
2
The function $f:[0,3] \to [1,29]$ defined by
$f(x) = 2x^3 - 15x^2 + 36x + 1$ is:
1
one–one and onto 2
onto but not one–one 3
one–one but not onto 4
neither one–one nor onto Go to Discussion
Jamia Millia Islamia Previous Year PYQ
Jamia Millia Islamia JAMIA MILLIA ISLAMIA MCA 2019 PYQ
Solution $f'(x) = 6x^2 - 30x + 36 = 6(x^2 - 5x + 6) = 6(x-2)(x-3).$
Sign chart:
• $f'$ > 0 for $x<2$; $f'$ < 0 for $2
Qus : 11
Jamia Millia Islamia PYQ
3
. Find the variance of the observation values taken in the lab: $4.2,\ 4.3,\ 4.0,\ 4.1$.
1
0.27 2
0.28 3
0.3 4
0.31 Go to Discussion
Jamia Millia Islamia Previous Year PYQ
Jamia Millia Islamia JAMIA MILLIA ISLAMIA MCA 2024 PYQ
Solution Mean $,\bar x=\dfrac{4.2+4.3+4.0+4.1}{4}=4.15$.
Deviations: $0.05,,0.15,,-0.15,,-0.05$.
Sum of squares $=0.0025+0.0225+0.0225+0.0025=0.05$.
Population variance $,s^2=\dfrac{0.05}{4}=0.0125$.
Sample variance $,s^2=\dfrac{0.05}{3}\approx0.0167$.
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