General Science & Current Affairs

General Science & Current Affairs

Staphylococcal food poisoning manifests within how much time after ingestion of contaminated food:

Staphylococcus aureus produces heat-stable enterotoxin preformed in food. After ingestion, toxin acts rapidly on gut causing vomiting, cramps and diarrhea within 2-6 hours. Short incubation distinguishes intoxication from infection requiring bacterial colonization and longer incubation periods.

Ref: Ananthanarayan, R. and Paniker, C.K.J., Textbook of Microbiology, 10th Edition, Chapter 21 Staphylococcus, discusses staphylococcal food poisoning, enterotoxin mechanism, short incubation 2-6 hours, clinical manifestations of intoxication, published by Orient BlackSwan.

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General Science & Current Affairs

In a regression model, a situation in which the error term is same or constant across all values of the independent vari

Ordinary least squares assumes homoscedasticity meaning error variance remains constant across independent variable range. Violation heteroscedasticity causes inefficient estimates. Graphical residual plots detect non-constant variance, while multicollinearity concerns correlation among predictors, not error variance consistency.

Ref: Gujarati, Damodar N. and Porter, Dawn C., Basic Econometrics, 5th Edition, Chapter 11 Heteroscedasticity, discusses homoscedasticity definition, OLS assumptions, constant error variance, detection and consequences of violation, published by McGraw Hill Education.

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If a constant 20 is subtracted from each of the value of X and Y, the regression coefficient of Y on X is:

Regression coefficient bxy = covariance XY divided by variance X. Adding or subtracting constant shifts origin but leaves deviations unchanged. Covariance and variance remain identical, so slope remains invariant. Only intercept changes while correlation and regression coefficient stay constant.

Ref: Gupta, S.C. and Kapoor, V.K., Fundamentals of Mathematical Statistics, 12th Edition, Chapter 10 Correlation and Regression, discusses properties of regression coefficients, invariance under change of origin, shift constant effects, published by Sultan Chand and Sons.

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General Science & Current Affairs

Which one of the following is NOT a non-parametric test?

Non-parametric tests avoid normality assumptions using ranks like Mann-Whitney, Kruskal-Wallis and Friedman. One-way ANOVA is parametric requiring normal distribution, homogeneity of variance and interval data to compare means via F-statistic, therefore not classified as non-parametric.

Ref: Daniel, Wayne W. and Cross, Chad L., Biostatistics: A Foundation for Analysis in the Health Sciences, 10th Edition, Chapter 9 Analysis of Variance, discusses parametric ANOVA assumptions versus non-parametric Mann-Whitney Kruskal-Wallis Friedman rank tests, published by Wiley.

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If a test statistic rejects the null hypothesis when it is true, then which type of error is made:

Type I error alpha denotes false positive rejecting true null hypothesis incorrectly. Type II error beta is failing to reject false null. Significance level directly controls Type I risk. Clinical trials carefully balance both errors to avoid spurious efficacy claims.

Ref: Daniel, Wayne W. and Cross, Chad L., Biostatistics: A Foundation for Analysis in the Health Sciences, 10th Edition, Chapter 8 Hypothesis Testing, discusses Type I and Type II errors, null hypothesis rejection, alpha beta and power concepts, published by Wiley.

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General Science & Current Affairs

Marital status of a group of people represents which variable:

Marital status categories single, married, divorced, widowed have no inherent quantitative order or rank. Nominal variables classify without ordering. Unlike ordinal variables, differences cannot be ranked numerically, and unlike discrete, values are labels rather than countable numbers.

Ref: P.S.S. Sundar Rao and J. Richard, Introduction to Biostatistics and Research Methods, 5th Edition, Chapter 2 Variables and Scales, discusses nominal ordinal interval ratio scales, marital status as nominal example, published by PHI Learning Private Limited.

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The mean of 5 observations is 4.4 and their variance is 8.24. If three of the observations are 1, 2 and 6. The other two

Let remaining be x,y. Sum =5×4.4=22, so x+y=13. Variance gives sum of squares 137.8. Then x²+y²=96. Solving quadratic yields 4 and 9. Verification matches mean and variance constraints simultaneously satisfying both equations.

Ref: Gupta, S.C. and Kapoor, V.K., Fundamentals of Mathematical Statistics, 12th Edition, Chapter 2 Measures of Central Tendency and Dispersion, discusses mean variance calculations, solving for missing observations using sum and sum of squares, published by Sultan Chand and Sons.

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General Science & Current Affairs

Sum of the deviation of the variable values 3, 4, 6, 8, 14 from their mean is:

Mean of values 3+4+6+8+14 =35 divided by 5 equals 7. Deviations -4, -3, -1, +1, +7 sum to zero algebraically. This property holds universally for any dataset because positive and negative deviations around arithmetic mean always exactly cancel.

Ref: Gupta, S.C. and Kapoor, V.K., Fundamentals of Mathematical Statistics, 12th Edition, Chapter 2 Measures of Central Tendency, discusses property of arithmetic mean where sum of deviations from mean always equals zero, deviation calculations, published by Sultan Chand and Sons.

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General Science & Current Affairs

When an investigator uses the data, which has already been collected by others, such data is called:

Primary data is collected firsthand for specific research purpose. Secondary data already exists gathered by other agencies like census, surveys, publications. Investigators using such secondhand sources save time and cost but must verify authenticity, definitions and sampling quality.

Ref: Kothari, C.R., Research Methodology: Methods and Techniques, 4th Edition, Chapter 5 Data Collection, discusses primary versus secondary data definitions, sources of secondary data, advantages limitations and evaluation criteria, published by New Age International Publishers.

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Mode can be determined by applying the formula:

For moderately skewed unimodal distribution, Karl Pearson established empirical relation Mode = 3 Median - 2 Mean. Mean pulls toward tail while median is robust. This formula connects central tendency measures, allowing mode estimation when distribution shape approximates asymmetry.

Ref: Gupta, S.C. and Kapoor, V.K., Fundamentals of Mathematical Statistics, 12th Edition, Chapter 2 Measures of Central Tendency, discusses Pearson empirical relationship between mean median and mode, skewed distributions formulas, published by Sultan Chand and Sons.

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A bag contains 7 green and 8 white balls. If two balls are drawn simultaneously, the probability that both are of the sa

Total ways to choose two from fifteen equals C15,2 =105. Favorable both green C7,2=21 plus both white C8,2=28 totals 49. Therefore probability is 49 divided by 105 which simplifies to 7/15, illustrating combination probability without replacement.

Ref: Gupta, S.C. and Kapoor, V.K., Fundamentals of Mathematical Statistics, 12th Edition, Chapter 3 Probability Theory, discusses combinations, same colour probability problems, hypergeometric distribution principles, without replacement sampling, published by Sultan Chand and Sons.

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General Science & Current Affairs

Indian Standard Time (IST) refers to the local time of which city?

Indian Standard Time is calculated from 82.5°E longitude passing through Mirzapur near Prayagraj Allahabad. This meridian is 5h30m ahead of Greenwich Mean Time. Central location ensures uniform time across India despite longitudinal span of nearly 30 degrees.

Ref: Majid Husain, Geography of India, 6th Edition, Chapter 1 Location Structure and Time, discusses Indian Standard Time, 82.5 degree east meridian passing through Mirzapur, IST calculation and significance, published by McGraw Hill Education.

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