SSC CGL Quant – Statistics & Probability – Level 2 · Exam Level · Sprint

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SSC CGL Quant – Statistics & Probability – Level 2 · Exam Level · Sprint – 14 questions, subject: Quantitative Aptitude. Every question has the correct answer with a one-line explanation; tap "Show Answer". Free practice for TNPSC, UPSC, SSC, Bank and RRB exams – Shanmugam IAS Academy, Coimbatore.

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1.  
The mean of 8 numbers is 20. If 5 is added to every number, the new mean is:

Correct Answer: D [25]

Explanation:

Adding a constant adds it to the mean: 20 + 5.

2.  
The standard deviation of 1, 3, 5, 7, 9 is:

Correct Answer: B [2√2]

Explanation:

Mean 5; squared deviations 16, 4, 0, 4, 16 → variance 40/5 = 8 → SD = √8 = 2√2.

3.  
The standard deviation of a data set is 4. If every value is multiplied by 3, the new standard deviation is:

Correct Answer: C [12]

Explanation:

SD is multiplied by |k| = 3 (36 would be the new variance).

4.  
The mean of 25 observations was 36. Later it was found that 48 had been wrongly read as 23. The correct mean is:

Correct Answer: A [37]

Explanation:

Wrong-Entry Fix: 36 + (48 − 23)/25 = 36 + 1 = 37.

5.  
Class A has 25 students with average marks 52, and class B has 15 students with average 60. The average of all 40 students is:

Correct Answer: C [55]

Explanation:

(25 × 52 + 15 × 60)/40 = 2200/40 = 55 (not 56, the plain average of 52 and 60).

6.  
Two dice are thrown together. The probability that the sum is 9 is:

Correct Answer: A [1/9]

Explanation:

(3,6), (4,5), (5,4), (6,3): 4/36 = 1/9.

7.  
Two dice are thrown together. The probability of a doublet (same number on both) is:

Correct Answer: B [1/6]

Explanation:

6 doublets out of 36.

8.  
Three coins are tossed together. The probability of getting at least two heads is:

Correct Answer: D [1/2]

Explanation:

HHH, HHT, HTH, THH = 4 of 8.

9.  

Directions (Q 22–24): The histogram shows the daily travel time of 40 employees of an office.

Data graphWhich class is the modal class?

Correct Answer: C [20–30 minutes]

Explanation:

Tallest bar: 14 employees in 20–30.

10.  
(Use the directions above – Q 22–24)
Data graphHow many employees travel for 30 minutes or more?

Correct Answer: B [13]

Explanation:

8 + 5 = 13.

11.  
(Use the directions above – Q 22–24)
Data graphThe mean daily travel time (using class mid-points) is:

Correct Answer: A [25.5 minutes]

Explanation:

Σfx = 15 + 150 + 350 + 280 + 225 = 1020; 1020 ÷ 40 = 25.5.

12.  
Two-quantity comparison
Quantity I: Mean of 3, 5, 7, 9, 11
Quantity II: Median of 2, 7, 8, 6, 4

Correct Answer: A [Quantity I > Quantity II]

Explanation:

QI = 35/5 = 7; QII: sorted 2, 4, 6, 7, 8 → 6.

13.  
Spot My Mistake“The median of 9, 2, 7, 4, 6 is 7 because 7 is the middle number.” The correct median is:

Correct Answer: D [6]

Explanation:

Sort first: 2, 4, 6, 7, 9 → middle value 6.

14.  
Reverse questionThe mean of five numbers is 30. Four of them are 24, 28, 35 and 37. The fifth number is:

Correct Answer: A [26]

Explanation:

5 × 30 − (24 + 28 + 35 + 37) = 150 − 124 = 26.

➤ Full notes, shortcuts and every answer explained – SSC CGL 2026 Quantitative Aptitude book (₹149): www.shanmugamiasacademy.in/study-materials/ssc-cgl-quantitative-aptitude

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