A Methods and Measurement Analyst for TimePiece, Inc., needs to develop a time standard for the task of attaching a watch to a wristband. In a preliminary study, he observed one of his workers perform this task five times, with the following results:

OBSERVATION $1,2,3,4,5$

Time $($seconds$)30,25,35,30,30$

a$.$ What is the observed time $($OT$)$ for this task? $(2)$

b$.$ What is the normal time $($NT$)$ for this task if the employee has a performance rating of $125\%?(2)$

c$.$ What is the standard time $($ST$)$ for this task if the employee has a performance rating of $100\%,$ and an allowance of twenty percent of the workday is used? $(2)$