There are 4 consecutive odd numbers (x1, x2, x3 and x4) and three consecutive even numbers (y1, y2 and y3). The average of the odd numbers is 6 less than the average of the even numbers. If the sum of the three even numbers is 16 less than the sum of the four odd numbers, what is the average of x1, x2, x3 and x4?
A. 30
B. 38
C. 32
D. 34
Answer: Option D
Solution(By Examveda Team)
According to given informationAverage of odd numbers = Average of even numbers - 6
$$ \Rightarrow \frac{{{x_1} + {x_2} + {x_3} + {x_4}}}{4} = $$ $$\frac{{{y_1} + {y_2} + {y_3}}}{3} - 6$$
$$ \Rightarrow \frac{{{x_1} + {x_2} + {x_3} + {x_4}}}{4} = $$ $$\frac{{{y_1} + {y_2} + {y_3} - 18}}{3}$$
$$ \Rightarrow 3\left( {{x_1} + {x_2} + {x_3} + {x_4}} \right) = $$ $$4\left( {{y_1} + {y_2} + {y_3}} \right) - 72$$
Also,
$$ \Rightarrow {y_1} + {y_2} + {y_3} = $$ $${x_1} + {x_2} + {x_3} + {x_4} - 16$$
$$ \Rightarrow {x_1} + {x_2} + {x_3} + {x_4} = $$ $${y_1} + {y_2} + {y_3} + 16$$ .....(i)
So we have,
$$ \Rightarrow 3\left( {{y_1} + {y_2} + {y_3} + 16} \right) = $$ $$4\left( {{y_1} + {y_2} + {y_3}} \right) - 72$$
$$ \Rightarrow 3{y_1} + 3{y_2} + 3{y_3} + 48 = $$ $$4{y_1} + 4{y_2} + 4{y_3} - 72$$
$$ \Rightarrow 4{y_1} + 4{y_2} + 4{y_3}$$ $$ - 3{y_1} - 3{y_2} - 3{y_3}$$ = 48 + 72
$$ \Rightarrow {y_1} + {y_2} + {y_3} = 120$$
$$ \Rightarrow {x_1} + {x_2} + {x_3} + {x_4}$$ = 120 + 16 = 136 [From (i)]
∴ Average of four odd numbers :
$$\eqalign{ & = \frac{{{x_1} + {x_2} + {x_3} + {x_4}}}{4} \cr & = \frac{{136}}{4} \cr & = 34 \cr} $$
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