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

Total possible outcomes = 2⁴ = 16.

The probability of getting no head (all tails) is 1/16.

Probability of getting at least one head = 1 − P(no head).

Therefore: 1 − 1/16 = 15/16.

Explanation

Given:

Brickwork = 100 cft

Mortar ratio = 1: 5

For rate analysis of brickwork, the standard quantity of cement for 100 cft of brickwork in 1:5 mortar is approximately 4 bags.