Question

1. jake has three cards with a number on each card. 12 20 ? the mean of the three numbers is 14. what is the number on the 3rd card? type a response

Explanation:

Step1: Recall mean formula

The mean $\bar{x}=\frac{\sum_{i = 1}^{n}x_{i}}{n}$. Here $n = 3$ and $\bar{x}=14$, so $\sum_{i=1}^{3}x_{i}=n\times\bar{x}=3\times14 = 42$.

Step2: Find sum of known numbers

The sum of the two known numbers is $12 + 20=32$.

Step3: Calculate the unknown number

Let the unknown number be $x$. Then $32+x = 42$, so $x=42 - 32=10$.

Answer:

10