The average length of 6 snakes is 80 cm. If the average length of one

Question

The average length of 6 snakes is 80 cm. If the average length of one third of the snakes is 70 cm, what is the average of the other snakes?

A. 75.
B. 85.
C. 90.
D. 94.
E. 100.

This is a  PS Butler Question

Check the links to other Butler Projects:

Data Sufficiency Butler  
  Critical Reasoning Butler  
  Reading Comprehension Butler  
  Data Insights Butler

APram · Answer

Sum of length of 6 snakes = 480
Sum of length of 2 snakes = 140
Sum of length of 4 snakes = 340
Average of length of 4 snakes = 85

Option B

aadityat · Answer

TOTAL = 480 (80X6)
FISRT HALF = 140 (70X2)
REST = 340 (480-140)
HENCE THE AVERAGE IS = 340/4 = 85
OPTION B

Souradeep17 · Answer

Avg. length of 6 snakes is 80
Total length = 6*80=480
Avg. length of 2 snakes is 70
Total =140

Avg length of the other 4 snakes = (480-140)/4=85

ManishaPrepMinds · Answer

Let's solve this question using  deviation  method:

Overall average  = 80 cm   
 ⇒ Total length of 6 snakes = 6 × 80 =  480 cm

Two snakes average 70cm    
 ⇒ Each is    10 cm below    the average 
 ⇒ Combined deviation = 2 × (–10) =  –20 cm

To maintain a total of 480 cm, the remaining 4 snakes must contribute:    
 ⇒ +20 cm in total

Distribute +20 cm evenly across the 4 remaining snakes     
 ⇒ +20 ÷ 4 =  +5 cm  per snake

So, each of the remaining 4 snakes is:
 ⇒ 80 + 5 =  85 cm    
  Average of the other 4 snakes = 85 cm

I’ve written a short article on this strategy, especially for those who prefer to visualize rather than formulas. 
  The Balancing Act of Averages

Prep Toolkit