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Statistics Test - 17

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Statistics Test - 17
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  • Question 1
    1 / -0
    Find odd one out:
    Mean, Median, Mode, Variance
    Solution
    Mean, median, mode are the measures of the central tendencies. Therefore, the odd one is the variance.
  • Question 2
    1 / -0
    The mean of $$a, b, c, d$$ and $$e$$ is $$28$$. If the mean of $$a, c$$ and $$e$$ is $$24$$, what is the mean of $$b$$ and $$d$$?
    Solution
    Formula used:
    $$\text{Arithmetic mean}= \dfrac{\text{Sum of given numbers}}{\text{Total numbers}}$$

    Given $$\Rightarrow$$ $$\dfrac{a+b+c+d+e}{5}=28$$ and $$\dfrac{a+c+e}{3} =24 $$
    To find $$\Rightarrow$$ $$\dfrac{b+d}{2}$$ which is nothing but the mean of $$b$$ and $$d$$.

    $$\begin{aligned}{}\dfrac{{a + b + c + d + e}}{5} &= 28\\a + b + c + d + e& = 140\quad \dots (i)\end{aligned}$$

    Also,
    $$\begin{aligned}{}\dfrac{{a + c + e}}{3} &= 24\\a  + c + e& = 72\quad \dots (ii)\end{aligned}$$

    By using $$(i)$$ and $$(ii)$$,
    $$\begin{aligned}{}a + b + c + d + e &= 140\\b + d + 72 &= 140\\b + d &= 68\\\dfrac{{b + d}}{2} &= 34\end{aligned}$$

    Hence, option $$D$$ is the correct answer.
  • Question 3
    1 / -0

    Directions For Questions

    Study the following table and answer the questions based on it.
    Number of Candidates Appeared, Qualified and Selected in a Competitive Examination from Five States Delhi, H.P, U.P, Punjab and Haryana Over the Years $$1994$$ to $$1998$$
    DelhiH.P.U.PPunjabHaryana
    YearAppQualSelAppQualSelAppQualSelAppQualSelAppQualSel
    $$1997$$$$8000$$$$850$$$$94$$$$7800$$$$810$$$$82$$$$7500$$$$720$$$$79$$$$8200$$$$680$$$$85$$$$6400$$$$700$$$$75$$
    $$1998$$$$4800$$$$500$$$$48$$$$7500$$$$800$$$$65$$$$5600$$$$620$$$$85$$$$6800$$$$600$$$$70$$$$7100$$$$650$$$$75$$
    $$1999$$$$7500$$$$640$$$$82$$$$7400$$$$560$$$$70$$$$4800$$$$400$$$$48$$$$6500$$$$525$$$$65$$$$5200$$$$350$$$$55$$
    $$2000$$$$9500$$$$850$$$$90$$$$8800$$$$920$$$$86$$$$7000$$$$650$$$$70$$$$7800$$$$720$$$$84$$$$6400$$$$540$$$$60$$
    $$2001$$$$9000$$$$800$$$$70$$$$7200$$$$850$$$$75$$$$8500$$$$950$$$$80$$$$5700$$$$485$$$$60$$$$4500$$$$600$$$$75$$

    ...view full instructions

    For which state the average number of candidates selected over the years is the maximum?
    Solution
    The average number of candidates selected over the given period for various states are:

    For Delhi $$= \dfrac {94 + 48 + 82 + 90 + 70}{5} $$

                     $$= \dfrac {385}{5} = 76.8$$

    For U.P. $$= \dfrac {78 + 85 + 48 + 70 + 80}{5} $$

                  $$= \dfrac {361}{5} = 72.2$$

    For Punjab $$= \dfrac {85 + 70 + 65 + 84 + 60}{5} $$

                       $$= \dfrac {364}{5} = 72.8$$

    For Haryana $$= \dfrac {75 + 75 + 55 + 60 + 75}{5} $$

                          $$= \dfrac {340}{5} = 68$$

    The average is maximum for Delhi.
  • Question 4
    1 / -0
    Find odd man out: 
    Standard Deviation, Variance, Mean, Quartile deviation.
    Solution
    Standard deviation, variance, quartile deviation gives the dispersion of the data. Therefore the odd one is mean.
  • Question 5
    1 / -0
    Variance can be calculated using:
    Solution
    Variance gives the degree to which the numerical data tend to spread about the value.

    Variance is given by $$\dfrac{\sum x^2}{n}-(\dfrac{\sum x}{n})^2$$
  • Question 6
    1 / -0

    Directions For Questions

    Study the following table and answer the questions based on it.
    Expenditure of a Company (in Lakh Rupees) per Annum Over the given years.
    YearSalaryFuel and TransportBonusInterest on LoansTaxes
    $$1998$$$$288$$$$98$$$$3.00$$$$23.4$$$$83$$
    $$1999$$$$342$$$$112$$$$2.52$$$$32.5$$$$108$$
    $$2000$$$$324$$$$101$$$$3.84$$$$41.6$$$$74$$
    $$2001$$$$336$$$$133$$$$3.68$$$$36.4$$$$88$$
    $$2002$$$$420$$$$142$$$$3.96$$$$49.4$$$$98$$

    ...view full instructions

    What is the average amount of interest per year which the company had to pay during this period?
    Solution
    Average amount of interest paid by the Company during the given period
    $$= Rs. \left [\dfrac {23.4 + 32.5 + 41.6 + 36.4 + 49.4}{5}\right ]lakhs$$
    $$= Rs. \left [\dfrac {183.3}{5}\right ]lakhs$$
    $$= Rs. 36.66\ lakhs$$
  • Question 7
    1 / -0
    Mean of marks obtained by $$10$$ students is $$30$$.
    Marks obtained are $$25,30,21,55,47,10,15,x,45,35$$.
    Find the value of $$x$$.
    Solution
    Let $$u$$ be the average marks of the class.
    $$\therefore u=\dfrac{25+30+21+55+47+10+15+x+45+35}{10}=\dfrac{283+x}{10}$$
    But $$u=30$$.
    So,$$30=\dfrac{283+x}{10}$$.
    $$\therefore x=17$$
    Ans-Option D
  • Question 8
    1 / -0
    Find the mean deviation about the mean of the following data:
    $$15,17,10,13,7,18,9,6,14,11$$.
    Solution
    Let the mean of data be $$u=\dfrac{\sum x_i}{n}=\dfrac {120}{10}=12$$
    Calculating the deviation : $$|x_i-u|$$ we get,
    $$3,5,-2,1,5,6,3,6,2,1$$.
    $$\therefore M.D (u)= \dfrac{\sum{|x_i-u|}}{n}= \dfrac{34}{10}=3.4$$
    Thus, $$M.D(u) =3.4$$.
    Ans- Option $$D$$
  • Question 9
    1 / -0
    Calculate variance for following data : 
    Length of wire$$1700-1900$$$$1900-2100$$$$2100-2300$$$$2300-2500$$$$2500-2700$$
    Number$$10$$$$16$$$$20$$$$8$$$$6$$
    Solution
    $$\bar { x } =\cfrac { \sum { Fx }  }{ \sum { F }  }=\cfrac{128800}{60}=2146.66 $$
    $${\sigma}^{2}=\cfrac { \sum { F{ ( }x-\bar { x } )^{ 2 } }  }{ \sum { F }  }=\cfrac{3349333.27}{60}=55822.22$$

  • Question 10
    1 / -0
    Means of two samles of sizes $$50,100$$ respectivly are $$54.1,50.3$$ and SD are $$8$$ and $$7$$. The combined SD of two samples is
    Solution
    $${n}_{1}=50  $$ & $$  {n}_{2}=100.$$
    $${\bar x}_{1}=54.1 $$ & $${\bar x}_{2}=50.3$$.
    $${\sigma}_{1}=8$$ & $${\sigma}_{2}=7.$$
    $$\bar x=\cfrac{{n}_{1}{\bar x}_{1}+{n}_{2}{\bar x}_{2}}{{n}_{1}+{n}_{2}}=\cfrac{50\times 54.1+100\times 50.3}{150}=51.567$$.
    $${\sigma}_{1}={\bar x}_{1}-\bar x=54.1-51.56=2.53$$.
    $${\sigma}_{2}={\bar x}_{2}-\bar x=50.3-51.56=-1.26$$.
    $${ \sigma  }^{ 2 }({ n }_{ 1 }+{ n }_{ 2 })={ n }_{ 1 }({ \sigma  }_{ 1 }^{ 2 }+{ d }_{ 1 }^{ 2 })+{ n }_{ 2 }({ \sigma  }_{ 2 }^{ 2 }+{ d }_{ 2 }^{ 2 })=50(60+6.4)+100(49+1.58)$$
    $${\sigma}^{2} (150)=3520+5058$$
    $$ {\sigma}^{2}=\cfrac{8578}{150}=57.18$$ 
    $$\sigma=7.56$$
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