We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. cookie policy and privacy policy.
 
+0  
 
0
253
2
avatar+480 

2, 11, 20, 29...

 

Which term in this sequence is 227?

 

 

A)18th

B)24th

C)25th

D)26th

E)27th

 Nov 29, 2018
 #1
avatar+5797 
+1

\(\text{Assuming we start the sequence numbering at 1 so that }s_1 = 2\\ s_k = 2+9(k-1)\\ 227 = 2 + 9(k-1)\\ 225 = 9(k-1)\\ k -1 = 25\\ k=26\)

 

choice (D)

 Nov 29, 2018
 #2
avatar+23077 
+10

2, 11, 20, 29...
Which term in this sequence is 227?

 

\(\begin{array}{|rcll|} \hline & \text{difference} \\ \hline a_1=2 \\ & \color{red}9 \\ a_2=11 \\ & \color{red}9 \\ a_3=20 \\ & \color{red}9 \\ a_4=29 \\ \ldots \\ a_n =227 \\ \hline \end{array}\)

 

This is a Arithmetic Sequence.

\(\text{Formula:}~ \boxed{a_n=a_1 + (n-1)d,\text{ with } a_1=2\text{ and }d = 9 }\)

 

\(\begin{array}{ll} \text{where:}\\ & a_1~ \text{ is the first term, and} \\ & d~ \text{ is the difference between the terms (called the "common difference")} \\ \end{array} \)

 

\(\begin{array}{|rcll|} \hline 227 &=& 2 + (n-1)9 \\ 227 &=& 2 + 9n-9 \\ 227 &=& 9n-7 \\ 227+7 &=& 9n \\ 234 &=& 9n \\ n &=& \dfrac{234}{9} \\ \mathbf{n} & \mathbf{=} & \mathbf{26} \\ \hline \end{array}\)

 

laugh

 Nov 30, 2018

13 Online Users