Answer :

We know that

⇒ Sum of observations = Mean ×Total number of observations

Sum of 35 observations = 20×35=700

Sum of first 18 observations = 15×18=270

Sum of last 18 observations = 25× 18=450

While adding first 18 observations and last 18 observations, we add 18^{th} observation twice so,

18^{th} observation= Sum of first 18 observations + Sum of last 18 observations - Sum of 35 observations

⇒ 18^{th} observation= 270 + 450 – 700 =20

Rate this question :

If the mean of thMHB - Math Part-I

The mean of nine MHB - Math Part-I

There are 10 obseMHB - Math Part-I

What is the mode MHB - Math Part-I

The mean salary oMHB - Math Part-I

Mean of 100 obserMHB - Math Part-I

What is the mediaMHB - Math Part-I

If <a name="MTBlaMHB - Math Part-I

There are 40 studMHB - Math Part-I

In the following MHB - Math Part-I