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The sequence 24, $a$, $b$, $c$, $d$ 60 is arithmetic. What is the value of $a+b+c+d$?

 Jan 13, 2024

Best Answer 

 #1
avatar+290 
+1

60 - 24 = 36, so we can divide 36 by 5 because we have to add a number 5 times, and we get 7.2, so the arithmetic sequance is growing by 7.2 each progressive term.

 

24, 24 + 7.2, 24 + 14.4, 24 + 21.6, 24 + 28.8, 60

 

a = 31.2

b = 38.4

c = 45.6

d = 52.8

 

a + b + c + d = 168

 

Answer: 168

 Jan 13, 2024
 #1
avatar+290 
+1
Best Answer

60 - 24 = 36, so we can divide 36 by 5 because we have to add a number 5 times, and we get 7.2, so the arithmetic sequance is growing by 7.2 each progressive term.

 

24, 24 + 7.2, 24 + 14.4, 24 + 21.6, 24 + 28.8, 60

 

a = 31.2

b = 38.4

c = 45.6

d = 52.8

 

a + b + c + d = 168

 

Answer: 168

DS2011 Jan 13, 2024
 #2
avatar+129849 
+1

Here's one  more way

 

Sum of arith series =  ( first term + last term) (number of  terms)  / 2

 

( 24  + 60  )  ( 6)  / 2 =   252

 

So

 

252  - 24 - 60  =  252  - 84 =   168

 

 

cool cool cool

 Jan 13, 2024
edited by CPhill  Jan 13, 2024

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