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Tamil Nadu State Board · Statistics

TAMIL NADU STATE BOARD CLASS 12 STATISTICS 2025

2025 · 33 questions · First 10 Solutions Free
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Q12 mcq
An additive model of time series with components, T, S, C and I is :
a.
Y=TΓ—S1CΓ—I
b.
Y=TΓ—SΓ—CΓ—I
c.
Y=TΓ—SΓ—C1I
d.
Y=T1S1C1I Correct Answer
Step-by-Step AI Explanation
Verified Method
In the additive model of time series, the observed value is represented as the sum of its components: $Y=T+S+C+I$ where $T$ = Trend, $S$ = Seasonal, $C$ = Cyclical, and $I$ = Irregular. Among the given options, the intended additive-form option is D, while A, B, and C show multiplicative symbols and are therefore not additive models.
Q13 mcq
The first National Statistics Day was celebrated on ____________.
a.
June 29, 2007
b.
April 29, 2007
c.
July 29, 2007
d.
May 29, 2007 Correct Answer
Step-by-Step AI Explanation
Verified Method
The first National Statistics Day in India was celebrated on June 29, 2007, in honour of Prof. P. C. Mahalanobis. Hence the correct option is (A). The other dates are incorrect.
Q14 mcq
Vital Index measures :
a.
infant mortality rate
b.
birth - death ratio Correct Answer
c.
general fertility rate
d.
rate of vital event
Step-by-Step AI Explanation
Verified Method
Vital Index measures the ratio of births to deaths. It is given by the number of live births per 100 deaths. Therefore, the correct answer is (B) birth-death ratio. The other options refer to different demographic measures.
Q15 mcq
Rates of Vital events are usually measured as :
a.
per thousand Correct Answer
b.
per ten lakh
c.
per hundred
d.
per ten thousand
Step-by-Step AI Explanation
Verified Method
Rates of vital events are usually expressed per thousand population. Hence the correct answer is (A) per thousand.
Q16 short answer
In a recent survey, conducted among 2000 randomly selected graduates in a district, 367 of them are IAS aspirants. Calculate the proportion of IAS aspirants among the graduates in the district.
Step-by-Step AI Explanation
Verified Method
The proportion of IAS aspirants among the graduates is $$\frac{367}{2000}=0.1835$$ So, the proportion is $0.1835$, or $18.35\%$.
Q17 short answer
Define degrees of freedom.
Step-by-Step AI Explanation
Verified Method
Degrees of freedom are the number of independent values that are free to vary after certain constraints have been imposed. In general, if $n$ observations are subject to $k$ constraints, then degrees of freedom $= n-k$.
Q18 short answer
What are the assumptions of ANOVA ?
Step-by-Step AI Explanation
Verified Method
The main assumptions of ANOVA are: 1. The samples are independent random samples. 2. The populations are normally distributed. 3. The population variances are equal, i.e., homogeneity of variance. 4. The observations within each group are randomly selected and independent. These assumptions must hold for valid application of ANOVA.
Q19 short answer 12 marks
Given that $\operatorname{cov}(x, y)=9.3$, variance of $x=10.1$, variance of $y=11.9$. Find $r$.
Step-by-Step AI Explanation
Verified Method
Given: $$\operatorname{cov}(x,y)=9.3,\quad \sigma_x^2=10.1,\quad \sigma_y^2=11.9$$ So, $$\sigma_x=\sqrt{10.1},\qquad \sigma_y=\sqrt{11.9}$$ The correlation coefficient is $$r=\frac{\operatorname{cov}(x,y)}{\sigma_x\sigma_y}$$ Substituting the values, $$r=\frac{9.3}{\sqrt{10.1}\,\sqrt{11.9}}=\frac{9.3}{\sqrt{120.19}}$$ Now, $$\sqrt{120.19}\approx 10.963$$ Hence, $$r\approx \frac{9.3}{10.963}\approx 0.848$$ Therefore, the correlation coefficient is $r\approx 0.85$.
Q20 short answer
What are the types of regression ?
Step-by-Step AI Explanation
Verified Method
The two types of regression are: 1. Regression of $Y$ on $X$ 2. Regression of $X$ on $Y$ These are called the two regression lines. They are used to estimate one variable from the other.
Q21 short answer
What is circular test ?
Step-by-Step AI Explanation
Verified Method
Circular test is a test used to check the consistency or reliability of the two regression equations. It is based on the property that the product of the two regression coefficients should be equal to the square of the correlation coefficient, that is, $$b_{xy} \cdot b_{yx} = r^2.$$ If this relation is satisfied, the regression equations are said to be consistent.
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Q22 short answer
What is a time series ?
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Q23 short answer
What is the formula used to compute infant mortality rate ?
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Q24 short answer
The number of children born in a city during a period was 3,907 and the total population of the city in that period was 20,00,000. Find the crude birth rate of the city.
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Q25 long answer
Describe Decision Table.
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Q26 long answer
State the properties of $\chi^2$ distribution.
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Q27 long answer
Write the model ANOVA table for one-way classification.
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Q28 long answer
Write any three uses of correlation.
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Q29 short answer
What is cyclical variation ?
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Q30 short answer
State the characteristics of a project.
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Q31 long answer
Calculate the consumer price index number for 2015 on the basis of 2000 from the following data by using the Aggregate Expenditure method. 2000 2015 Wheat 10 15 20 Rice 12 30 36 Ghee 2 160 200 Sugar 4 40 40 Price Commodity Quantity
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Q32 long answer
The number of women at reproductive age in a district is 70,000. Also the number of live births and infant deaths registered in the district are respectively 10,000 and 70. Which mortality rate you will calculate ? What is its value ?
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Q32 long answer
The following are the information about the number of persons who are affected by Diabetes and Lung Cancer and the number of persons died due to each cause of death during a calendar year in two different districts: Affected Died Affected Died Diabetes 20,000 325 22,000 400 Lung cancer 19,500 300 21,225 380 District A No. of persons District B No. of persons Cause of Death Find the Illness specific death rates for the two districts. Also, compare health conditions of both the districts with reference to these two causes of death.
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Q33 short answer
Given the following lines of regression $4X-5Y=-33$ and $20X-9Y=107$. Find the mean values of $X$ and $Y$.
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Q33 long answer
A test was conducted with 6 students before and after the training programme. Their marks were recorded and tabulated as shown below. Test whether the training was helpful in improving their scores. Before training 100 160 113 122 120 105 After training 120 155 120 128 115 100
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Q34 long answer
A company producing LED bulbs finds that mean life span of the population of its bulbs is 2000 hours with a standard deviation of 150 hours. A sample of 100 bulbs randomly chosen is found to have the mean life span of 1950 hours. Test, at 5% level of significance, whether the mean life span of the bulbs is significantly different from 2000 hours.
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Q34 long answer
Estimate the value of production for the year 1995 by using the method of least squares from the following data. Year 1990 1991 1992 1993 1994 Production (1000 tons) 70 72 88 90 92
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Q35 long answer
A test was given to five students taken at random from XII class of three schools of a town. The individual scores are : School I 9 7 6 5 8 School II 7 4 5 4 5 School III 6 5 6 7 6 Carry out the one-way ANOVA.
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Q35 long answer
Following data gives the yield of foodgrains in India for the years 1990 - 91 to 1999 - 2000. Find the trend values using 4 - year moving averages. Year 1990-91 91-92 92-93 93-94 94-95 95-96 96-97 97-98 98-99 1999-2000 Yield (kg/hectare) 626 734 535 727 652 715 756 860 909 798
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Q36 short answer
Calculate the regression equation of X on Y from the data given below, $x$ 7 4 6 9 3 8 $y$ 8 5 4 8 3 6
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Q36 short answer
A random sample of 5 college students is selected and their marks in Tamil and English are found to be : Tamil 85 60 73 40 90 English 93 75 65 50 80 Calculate Spearman’s rank correlation coefficient.
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Q37 long answer
A normal population has mean $\mu$ (unknown) and variance 9. A sample of size 9 observations has been taken and its variance is found to be 5.4. Test the null hypothesis $H_0 : \sigma^2=9$ against $H_1 : \sigma^2>9$ at 5% level of significance.
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Q37 long answer
Calculate the price indices from the following data by applying (1) Laspeyre’s method (2) Paasche’s method and (3) Fisher ideal number by taking 2010 as the base year. Prices Quantities Prices Quantities A 20 10 25 13 B 50 8 60 7 C 35 7 40 6 D 25 5 35 4 Commodity 2010 2011
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Q38 long answer
The following are the information about the number of persons who are affected by Diabetes and Lung Cancer and the number of persons died due to each
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