Question

the arithmetic mean of the following data is 7 find a+b
pls answer it i will mark as brianliest pls help​

Answer 1

The value of (b) a + b = 2.

Step-by-step explanation:

The given data are:

x    4    6   7    9

f     a   4    b    5

The arithmetic mean = 7

To find, the value of (a + b) = ?

Arithmetic mean =$\dfrac{4(a)+6(4)+7(b)+9(5)}{a+4+b+5}$

⇒ $\dfrac{4(a)+6(4)+7(b)+9(5)}{a+4+b+5}=7$    .....(1)

⇒ $\dfrac{4a+24+7b+45}{9+a+b}=7$

⇒$63+7a+7b=69+4a+7b$

⇒$7a+7b-4a-7b=69-63$

⇒$3a=6$

⇒$a=2$

Put a = 2 in (1), we get

b = 0

∴ a + b = 2 + 0 = 2

Hence, the value of (b) a + b = 2.