Life-time of 400 tubes tested in a company is distributed as follows UPSC Mains 2011 Question with answer

Life-time of 400 tubes tested in a company is distributed as follows

Life-Time (hours)	No. of tubes
300-399	14
400-499	46
500-599	58
600-699	76
700-799	68
800-899	62
900-999	48
1000-1099	22
1100-1199	6

 

 

 

 

 

 

Determine:

i.                 Relative frequency of sixth class

Relative frequency of 6^th class = no of tubes in 6^th class to the total no of tubes

Therefore R.F of 6^th class = 62/400 = 31/200

 

ii.                Percentage of tubes whose lifetime does not exceed 600 hours

No of tubes whose lifetime does not exceed 600 hours is 14+46+58 = 118

Total no of tubes = 400

% of tubes whose lifetime does not exceed 600 hours = (118/400)*100 = 29.5%

 

iii.               % of tubes whose lifetime are greater than or equal to 900 hours.

 

No of tubes whose lifetime are greater than or equal to 900 hours = 48+22+6 = 76

% of tubes whose lifetime are greater than or equal to 900 hours = (76/400)*100 = 19%

 

iv.              % of tubes whose lifetime is atleast 500 but less than 1000 hours.

No of tubes whose lifetime is atleast 500 but less than 1000 hours = 58+76+68+62+48= (312/400)*100  = 78%