Question

The sum of five numbers is 260.The average of first two numbers is 30 and the average of last two numbers is70. What is the third number?

Answer 1

Answer:

Step-by-step explanation:

a+b+c+d+e=260

⇒a+b /2 =30

⇒ a+b=60

⇒ d+e /2 =70

⇒ d + e =140

⇒ 60+c+140=260

⇒ c = 60

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Answer 2

The third number is 60

Step-by-step explanation:

Formula : $Average = \frac{\text{Sum of all observations}}{\text{No. of observations}}$

We are given that The average of first two numbers is 30

$30=\frac{\text{Sum of first two numbers}}{2}\\30 \times 2 = \text{Sum of first two numbers}\\60 = \text{Sum of first two numbers}$

The average of last two numbers is 70.

$70 = \frac{\text{Sum of last two numbers}}{2}\\140 = \text{Sum of last two numbers}$

Let the third number be x

We are given that The sum of five numbers is 260.

260=60+x+140

260-200=x

60=x

Hence The third number is 60

#learn more:

Find the average of 12 number if first 8numbers average is 21 find the average of last 4 numbers

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