Question

Please any one help me​

Answer 1

k=30

Explanation:

The formula for calculating the mean from a frequency table is:

`\displaystyle \overline{x} = ( \sum \: fx)/( \sum f)`

we have

• 
  `\sum f = 30`
• 
  `\sum f x= 120 + 3k`
• 
  `\overline{x} = 7`

So our equation is

`\displaystyle 7= ( 120 + 3k)/(30) \\ \implies (120 + 3k)/(30) = 7`

Solving the equation yields:

`\implies 120 + 3k = 210 \\ \implies 3k = 90 \\ \implies \boxed{k = 30}`

Answer 2

k = 30

Explanation:

The formula for the mean is:

`\boxed{\displaystyle \text{Mean}=\overline{x}=(\sum fx)/(\sum f)}`

where:

• x = data value
• f = frequency of each x

Given:

`\displaystyle \sum f=30`

`\displaystyle \sum fx=120+3k`

`\overline{x}=7`

Substitute the given values into the formula and solve for k:

`\implies 7=(120+3k)/(30)`

Multiply both sides by 30 to eliminate the denominator on the right side:

`\implies 210=120+3k`

Subtract 120 from both sides:

`\implies 90=3k`

Divide both sides by 3:

`\implies k=30`

Therefore, k = 30.