Statistics Practice Question | 20 September 2021

Question of The Day20-09-2021

The average of 25 observations is 11. An observation is removed due to which average decreases by 0.4 units. What is the value of observation that is removed?

Answer

Correct Answer : b ) 20.6

Explanation :

Quick Approach

Observation removed = New average + Number of observations × (New Average – Original average)

⇒ Observation removed = (11 – 0.4) + 25 × 0.4

⇒ Observation removed = 10.6 + 10 = 20.6

Hence, (b) is the correct answer.

Basic Approach

The average of 25 observations is 11

Sum of all the observations = 25 * 11 = 275

Let the value of observation which is removed is x

According to the question,

The average is decreased by 0.4

New average = 11 – 0.4 = 10.6

New sum of observations = 24 * 10.6 = 254.4

Now, according to the question

275 – x = 254.4

x = 20.6

Hence, (b) is the correct answer.

Such type of question is asked in various government exams like SSC CGL, SSC MTS, SSC CPO, SSC CHSL, RRB JE, RRB NTPC, RRB GROUP D, RRB OFFICER SCALE-I, IBPS PO, IBPS SO, RRB Office Assistant, IBPS Clerk, RBI Assistant, IBPS RRB OFFICER SCALE 2&3, UPSC CDS etc.

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