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%
