General Aptitude & Statistics

General Aptitude & Statistics

Heavy floods in Kerala this year led to the outbreak of which of the following diseases?

Kerala's 2018 floods caused waterlogging contaminating water with Leptospira from rodent urine. Human contact with floodwater led to leptospirosis surge presenting fever, myalgia, jaundice. Post-flood surveillance documented increased cases requiring doxycycline prophylaxis.

Ref: Anil S. et al., Indian Journal of Medical Research, 2019, Volume 149, Post-Flood Leptospirosis Outbreak in Kerala, discusses flood-associated Leptospira transmission, epidemiology during 2018 Kerala floods, waterborne zoonotic outbreak investigation and public health response.

View Details

General Aptitude & Statistics

Grass appears green because it

Grass contains chlorophyll a and b absorbing blue and red wavelengths for photosynthesis, reflecting middle green light around 550 nm. Human cones perceive reflected green, so foliage appears green though pigments actually utilize other spectral regions efficiently.

Ref: Taiz L., Zeiger E., Møller I.M. and Murphy A., Plant Physiology and Development, 6th Edition, Sinauer Associates, Chapter 9 Photosynthesis Light Reactions, discusses chlorophyll absorption spectra, reflection of green light, and why plants appear green to human vision.

View Details

General Aptitude & Statistics

Who is known as the father of Nuclear physics?

Ernest Rutherford discovered nucleus via gold foil scattering, proposing planetary atomic model and nuclear transmutation. His work identified alpha, beta radiations, proton concept, establishing experimental nuclear physics foundations and earning 1908 Nobel Prize.

Ref: Rhodes R., The Making of the Atomic Bomb, Simon and Schuster, Chapter 2 Rutherford as Father of Nuclear Physics, discusses Ernest Rutherford's nuclear model, scattering experiments, atomic nucleus discovery and emergence of nuclear physics discipline.

View Details

General Aptitude & Statistics

Who invented the periodic table?

Dmitri Mendeleev in 1869 arranged elements by atomic weight and valency, leaving gaps predicting gallium, scandium. His periodic law revealed recurring chemical properties, forming basis for modern table despite later reordering by atomic number.

Ref: Ebbing D.D. and Gammon S.D., General Chemistry, 11th Edition, Cengage Learning, Chapter 7 The Periodic Table, discusses Mendeleev invention of periodic table 1869, periodicity, prediction of undiscovered elements and modern periodic law development.

View Details

General Aptitude & Statistics

The Nobel prize was given for the first time in the year

First Nobel Prizes established by Alfred Nobel's 1895 will were awarded in 1901. Physics to Röntgen, Chemistry to van't Hoff, Medicine to Behring, Literature to Prudhomme. Peace Prize shared, reflecting inaugural recognition of outstanding contributions.

Ref: Friedman R.M., The Politics of Excellence: Behind the Nobel Prize in Science, Times Books, Chapter 1 Inaugural 1901 Prizes, discusses first Nobel award year 1901, Alfred Nobel's will execution, and selection of laureates, published by Henry Holt.

View Details

General Aptitude & Statistics

The most appropriate measure of dispersion when the data are contaminated by outliners is:

Quartile deviation based on Q1 and Q3 is resistant to outliers because interquartile range excludes extreme 25% tails. Range, standard deviation and mean deviation use all values, so outliers distort them heavily.

Ref: Tukey J.W., Exploratory Data Analysis, Addison-Wesley, Chapter 2 Robust Measures, discusses quartile deviation as resistant measure of dispersion when data contaminated by outliers, interquartile range stability and robust statistics principles for skewed distributions.

View Details

General Aptitude & Statistics

For a normally distributed population, cumulative density function has the shape of

Cumulative distribution function of normal is integral of bell-shaped pdf, producing S-shaped sigmoid curve from 0 to 1. It rises slowly, steeply near mean, then plateaus, reflecting accumulating probability with inflection at median.

Ref: Ross S.M., Introduction to Probability Models, 12th Edition, Academic Press, Chapter 5 Normal Distribution, discusses cumulative density function shape as sigmoid, properties of normal cdf, probit function and central tendency characteristics of Gaussian distribution.

View Details

General Aptitude & Statistics

‘Random sampling’ means

Random sampling requires each population unit have known non-zero selection probability, governed by probability laws ensuring unbiased representation. It contrasts with haphazard or judgment sampling, enabling statistical inference and error estimation.

Ref: Cochran W.G., Sampling Techniques, 3rd Edition, Wiley, Chapter 2 Simple Random Sampling, discusses random sampling governed by probability theory, equal chance selection, unbiased estimators and population representation principles in survey methodology.

View Details

General Aptitude & Statistics

In a binomial distribution, if changes of getting success are 50% and we perform an exceedingly large number of trials,

De Moivre-Laplace theorem states binomial approximates normal when n large, especially with p=0.5 yielding symmetric distribution. Mean np and variance npq approach bell curve, enabling normal approximation with continuity correction for probability calculations.

Ref: Feller W., An Introduction to Probability Theory and Its Applications, Volume 1, 3rd Edition, Wiley, Chapter 7 Central Limit Theorem, discusses binomial to normal approximation when trials large and p=0.5, de Moivre-Laplace approximation and normal curve convergence.

View Details

General Aptitude & Statistics

In testing significance of hypothesis,

Type I error rejects true null, Type II fails to reject false null. Their consequences differ by field; in medicine false negatives may be fatal, in law false convictions severe. Therefore seriousness depends on context, not universally predetermined hierarchy.

Ref: Montgomery D.C. and Runger G.C., Applied Statistics and Probability for Engineers, 7th Edition, Wiley, Chapter 9 Hypothesis Testing, discusses Type I and Type II errors, power of test, and context-dependent seriousness of error types in decision making.

View Details

General Aptitude & Statistics

For studying association between two attributes, the most appropriate test procedure is

Association between categorical attributes is tested via chi-square test of independence. It compares observed contingency frequencies with expected under independence, using degrees of freedom (r-1)(c-1). Significant chi-square indicates non-random relationship.

Ref: Snedecor G.W. and Cochran W.G., Statistical Methods, 8th Edition, Iowa State University Press, Chapter 9 Chi-Square Tests, discusses association between attributes, contingency tables, independence testing and expected frequency calculations for categorical data.

View Details

General Aptitude & Statistics

In a single throw of two dice, what is the probability of getting a sum of 8 or 11?

Two dice have 36 equally likely outcomes. Sum 8 occurs in 5 combinations, sum 11 in 2 combinations. These events are mutually exclusive, so total favorable is 7, giving probability 7/36 for sum of 8 or 11.

Ref: Feller W., An Introduction to Probability Theory and Its Applications, Volume 1, 3rd Edition, Wiley, Chapter 7 Dice Problems, discusses sum distribution for two dice, mutually exclusive events, addition theorem and combinatorial probability calculations.

View Details