An industrial engineer is performing a time study and knows that 75 minutes are normally devoted to rest periods and lunch, but an allowance for unavoidable delay must be estimated. A ratio-delay work-sampling study was conducted, with the following results:

Activity ---- Number of Observations

Unavoidable delay= 29

Avoidable delay= 59 Other= 387

what allowance fraction should be used in setting the labor standard if allowances include unavoidable delay lunch and rest period? assume 480 minutes per shift