Statistics & Applications

Trends & Data

Medium

applied

The number of letters posted in a certain city on each day for a week is given as follows: 40, 55, 28, 25, 31, 52, 43. Which of the following is not an entry in the three-day moving averages?

✅ Correct Option: 4

The number of letters posted over the week: 40, 55, 28, 25, 31, 52, 43

A three-day moving average takes any 3 consecutive days, adds them, and divides by 3. The window moves one day at a time.

Days 1, 2, 3:

$(40 + 55 + 28) \div 3$

$= 123 \div 3$

$= 41$

Days 2, 3, 4:

$(55 + 28 + 25) \div 3$

$= 108 \div 3$

$= 36$

Days 3, 4, 5:

$(28 + 25 + 31) \div 3$

$= 84 \div 3$

$= 28$

Days 4, 5, 6:

$(25 + 31 + 52) \div 3$

$= 108 \div 3$

$= 36$

Days 5, 6, 7:

$(31 + 52 + 43) \div 3$

$= 126 \div 3$

$= 42$

The three-day moving averages are: 41, 36, 28, 36, 42

Checking the options against this list shows that 37 does not appear.

Therefore, 37 is not an entry in the three-day moving averages.

2026: 19 May Shift 1

For a certain data $(x_i, y_i)$ , $i = 1,2,...,7$ : $\sum_{i=1}^{7} y_i = 246$ and $\sum_{i=1}^{7} u_iy_i = 29$ , $\sum_{i=1}^{7} u_i^2 = 28$ where $u_i = x_i - 2004$ , then straight line trend by the method of least square is :

2026: 21 May Shift 1

Time series helps to

(A) derive conclusions after arranging the time series in a systematic manner.

(B) predict the future behavior of a variable.

(D) plan future operations.

Choose the correct answer from the options given below:

2025: 22 May Shift 2

If three year moving averages for five data items given by 16, 18, 20, 10, 21 are $x$ , $y$ and $z$ respectively, then:

2025: 30 May Shift 1

Increase in the number of patients in the hospitals due to heat stroke is:

2025: 26 May Shift 2

Match List-I with List-II

List-I	List-II
Time Series Component	Example
(A) Secular Variation	(I) Pandemic
(B) Seasonal Variation	(II) Recession in business
(C) Cyclic Variation	(III) Monthly sale of woolen cloths
(D) Irregular variation	(IV) Data regarding National income

Choose the correct answer from the options given below:

2026: 22 May Shift 2

A fire in a factory delaying production for some time is:

The number of letters posted in a certain city on each day for a week is given as follows: 40, 55, 28, 25, 31, 52, 43. Which of the following is not an entry in the three-day moving averages?

Solution

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