Question

Please any one help me​

Answer 1

Answer:

k=30

Step-by-step explanation:

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

$\displaystyle \overline{x} = \frac{ \sum \: fx}{ \sum f}$

we have

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

So our equation is

$\displaystyle 7= \frac{ 120 + 3k}{30} \\ \implies \dfrac{120 + 3k}{30} = 7$

Solving the equation yields:

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

Answer 2

Answer:

k = 30

Step-by-step explanation:

The formula for the mean is:

$\boxed{\displaystyle \text{Mean}=\overline{x}=\dfrac{\sum fx}{\sum f}}$

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:

$\implies 7=\dfrac{120+3k}{30}$

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.