RRB NTPC Previous Year Paper 03 — Kerala PSC PYQ Practice with Answers

Correct answer (Option D):\n\nA magnitude of 8-9 on the Richter scale indicates a great or catastrophic earthquake capable of causing total destruction, not a micro earthquake. Micro earthquakes typically have magnitudes below 2.0 and are rarely felt by humans.\n\nWhy others are wrong:\nOption A is correct as Charles Richter and Beno Gutenberg developed it in 1935. Option B is correct because the scale is logarithmic, meaning each whole number increase represents a ten-fold increase in measured amplitude. Option C is correct since the data for the scale is recorded by a seismometer.\n\nStudy tip:\nRemember that the Richter scale is open-ended, but earthquakes above magnitude 9 are extremely rare. Ground motion increases 10 times for each unit, while energy release increases by about 32 times.

Correct answer (Option B):\nGiven data in ascending order: 0, 0, 1, 1, 2, 2, x, 3, 3, 4, 5, 7\nTotal number of terms (N) = 12\nSince N is even, the median is the average of the (N/2)th and ((N/2) + 1)th terms.\n6th term = 2\n7th term = x\nFormula: Median = (6th term + 7th term) / 2\nGiven Median = 2.5\nStep 1: 2.5 = (2 + x) / 2\nStep 2: 5 = 2 + x\nStep 3: x = 5 - 2 = 3\nAnswer: x = 3. Option B is correct.\n\nWhy others are wrong:\nOption A is wrong because if x = 2, the median would be (2+2)/2 = 2. Option C and D give median values of 3 and 1 respectively, which break the condition.\n\nStudy tip:\nAlways count the number of data points first. If N is odd, the median is the exact middle term. If N is even, it is always the mean of the two central terms.

Correct answer (Option B):\n\nA Modem (Modulator-Demodulator) converts digital signals from a computer into analog signals (modulation) so they can travel over telephone lines or cables, and vice versa (demodulation).\n\nWhy others are wrong:\nOption A (WiFi) is a wireless networking technology utilizing radio waves, not a direct signal converter. Option C (Port) is a physical or virtual connection interface. Option D (USB) is a standard cable connection interface protocol.\n\nStudy tip:\nModem stands for MOdulator DEmodulator. It is essential for bridging digital computing hardware with analog communication infrastructure.

Correct answer (Option A):\n\nFormula: For a proportion a:b :: c:d, we have a × d = b × c.\nGiven: N:38 = 3:57\nStep 1: N × 57 = 38 × 3\nStep 2: 57N = 114\nStep 3: N = 114 / 57\nStep 4: N = 2\n\nLooking closer at the options, N = 2 matches Option D, but the fraction option format provided in the text has a typo where (a) is 2/3 and (d) is 2. Let's evaluate the ratio directly: 3/57 = 1/19. Thus N/38 = 1/19, which gives N = 2. Option D is correct.\n\nWhy others are wrong:\nOptions A, B, and C do not satisfy the proportion equality since 2/3, 1/3, or 3 multiplied by 57 does not equal 114.\n\nStudy tip:\nProportion problems can always be solved quickly by setting the product of the extremes equal to the product of the means.

Correct answer (Option D):\n\nFormula: Distance = Speed × Time\nStep 1: Initial Time = 5.5 hours. Distance = 50 × 5.5 = 275 km.\nStep 2: New Speed = 50 + 5 = 55 km/hr.\nStep 3: New Time = Distance / New Speed = 275 / 55 = 5 hours.\nStep 4: Time saved = 5.5 hours - 5 hours = 0.5 hours.\nStep 5: Convert to minutes: 0.5 × 60 = 30 minutes.\nOption D is correct.\n\nWhy others are wrong:\nOptions A, B, and C represent incorrect calculations of the time difference or fail to convert the fractional hour difference to minutes correctly.\n\nStudy tip:\nWhen distance remains constant, speed and time are inversely proportional. S₁ × T₁ = S₂ × T₂ can bypass calculating the absolute distance completely.