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Explanation

Standard Deviation measures spread.

If every observation is multiplied by 3, the spread also gets multiplied by 3.

Mean changes by 3x, and SD also changes by 3x.

Last verified on 21-08-2026

Explanation

• Variance is zero only when all observations have the same value.
• Variance measures dispersion (spread).
• Variance is calculated from squared deviations from the mean.
• Since squared deviations cannot be negative, variance cannot be negative.

Last verified on 21-08-2026

Explanation

Total balls = 5 red + 4 blue + 3 green = 12 balls

Number of blue balls = 4

We need probability that both balls drawn are blue, without replacement.

First ball blue = 4/12

Second ball blue = 3/11

Multiply them: (4/12) * (3/11) = 12/132 = 1/11

Last verified on 21-08-2016

Explanation

1. P is the daughter of R → R is parent of P

2. N is the brother of P → N and P are siblings. So N is also child of R

3. R is the wife of S → S is father of P and N

4. S is the father of T → T is also child of S

So S is father of N, P, and T.  

That means N and T are siblings.

Answer: Brother

Last verified on 21-08-2026

Explanation

The given conditions do not produce a valid complete seating arrangement.

Let B = 1; since A is second right of B, A = 3.

C sits opposite A, so C = 7; D is immediately left of C, so D = 6.

E is second left of D, giving E = 4. The remaining positions are 2, 5, and 8 for F, G, and H.

Because F is not adjacent to B, F = 5 and G must be immediately right of F, which conflicts with the already occupied position of D.

The conditions are internally inconsistent, so the position opposite G cannot be determined.

Last verified on 21-08-2026

Explanation

Facing north: 

1. H at one end, 3 between H and D → H _ D

2. A right of D → D A → H _ _ _ D A

3. 2 between A and G, and B left of G → A _ B G

4. C second left of E → E _ C

5. F not at ends

Final order: D A C E B G F H

Immediately left of A is D

Last verified on 21-08-2026

Explanation

• Students were randomly assigned to read books, and afterward their vocabulary scores increased significantly.
• Random assignment helps reduce the influence of other factors that may affect vocabulary performance.
• The improvement occurred after the reading intervention, strengthening the connection between reading and vocabulary development.
• This provides stronger evidence than simply observing that regular readers score higher.

Last verified on 21-08-2026

Explanation

• No other major educational change explains the improvement.
• The university introduced compulsory attendance, and examination results improved one year later.
• To reasonably connect attendance with better results, other possible causes should be ruled out.
• If no other major educational change occurred, the improvement is more likely to be associated with compulsory attendance.
• This assumption therefore strengthens the causal claim.

Last verified on 21-08-2026

Explanation

• Balanced investment in industrialization, environmental protection, and technological innovation promotes sustainable long-term development.
• The passage acknowledges that economic growth often accompanies industrialization.
• However, industrial expansion alone is not presented as sufficient for sustainable development.
• Nations investing in environmental protection and technological innovation achieve better long-term outcomes.
• Therefore, a balanced approach is the main message of the passage.

Last verified on 21-08-2026

Explanation

• Technology improves productivity but should not eliminate human judgment.
• The passage states that technological innovation has enhanced productivity across many sectors.
• However, excessive reliance on automation may weaken critical-thinking abilities.
• Independent judgment and ethical reasoning remain essential in important decisions.
• Therefore, sustainable technological advancement requires a balance between machine efficiency and human oversight.

Last verified on 21-08-2026