The sum of 6 consecutive integers is 393.What is the third number in this sequence?

解

T h e s u m o f 6 co n sec u t i v e in t e g ers i s 393. Wha t i s t h e t hi r d n u mb er in t hi s se q u e n ce ?

The number : 65

解答ステップ

Represent the numbers with

x

First number : x

Consecutive number 1 : x + 1

Consecutive number 2 : x + 2

Consecutive number 3 : x + 3

Consecutive number 4 : x + 4

Consecutive number 5 : x + 5

A.T.Q.:

x + x + 1 + x + 2 + x + 3 + x + 4 + x + 5 = 393

解く

x + x + 1 + x + 2 + x + 3 + x + 4 + x + 5 = 393 : x = 63

x + 1 = 63 + 1 = 64

x + 2 = 63 + 2 = 65

x + 3 = 63 + 3 = 66

x + 4 = 63 + 4 = 67

x + 5 = 63 + 5 = 68

The number : 65