Saturday, November 19, 2011

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

Share

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 6th class = no of tubes in 6th class to the total no of tubes

Therefore R.F of 6th 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%