🎓 NIMCET📅 Year: 2014📚 Mathematics🏷 Statistics Measures of Central Tendency
1
The average marks of boys in a class is 52 and that of girls is 42. The average marks of boys and girls
combined is 50. The percentage of boys in the class is
Given averages: Boys = 52, Girls = 42, Combined = 50.
Let the proportion of boys be \(p\) (so girls = \(1-p\)).
Weighted mean gives:
$$52p + 42(1-p) = 50$$
$$52p + 42 - 42p = 50 \Rightarrow 10p = 8 \Rightarrow p = 0.8.$$
Percentage of boys \(= 0.8 \times 100\% = \boxed{80\%}\).
🎓 NIMCET📅 Year: 2016📚 Mathematics🏷 Permutations and Combinations
1
There are $4$ books on fairy tales, $5$ novels and $3$ plays. In how many ways can they be arranged in the order books on fairy tales, novels and then plays so that books of same category are put together
Given:
$4$ books on fairy tales, $5$ novels, $3$ plays
The order of arrangement is fixed as:
Fairy Tales $\rightarrow$ Novels $\rightarrow$ Plays
Step 1: Arrange books within each category
Fairy tales books can be arranged among themselves $= 4!= 24$ ways
Novels can be arranged among themselves $= 5! = 120$ ways
Plays can be arranged among themselves $= 3! = 6$ ways
Step 2: Total number of arrangements
$= 4! \times 5! \times 3!$
$= 24 \times 120 \times 6$
$\therefore \boxed{= 17280 \text{ ways}}$
🎓 NIMCET📅 Year: 2020📚 Mathematics🏷 Vector
1
If a, b, c are three non-zero vectors with no two of
which are collinear, a + 2b is collinear with c and b + 3c is collinear with a , then | a + 2b + 6c | will
be equal to
🎓 NIMCET📅 Year: 2016📚 Mathematics🏷 Statistics Measures of Central Tendency
3
Suppose a population $A$ has $100$ observations $101,102,\ldots,200$ and another population $B$ has $100$ observations $151,152,\ldots,250$. If $V_A$ and $V_B$ represent variance of the two populations respectively, then $\dfrac{V_A}{V_B}$ is
Population $A$: $101, 102, \ldots, 200$
Population $B$: $151, 152, \ldots, 250$
Using Property:
Variance is independent of change of origin
i.e., if each observation is increased or decreased by a constant, variance remains unchanged
Here, each observation of $B$ = each observation of $A$ $+ 50$
$\Rightarrow$ Population $B$ is obtained by adding $50$ to each observation of population $A$
$\Rightarrow V_B = V_A$
$\therefore \dfrac{V_A}{V_B} = \boxed{1}$
🎓 NIMCET📅 Year: 2026📚 Mathematics🏷 Progressions
4
The arithmetic mean of two numbers a and b is 5, and the harmonic mean is 3.2. Find the numbers a and b.