List of top Quality and Reliability Questions

A repairable machine operated for 2400 hours in a year and for that year the machine broke down 8 times. The mean time to repair including waiting time is found to be 20 hours for that year.
If the mean time to repair including waiting time could have been reduced to 10 hours for that year, then the improvement in the availability of that machine would be _____ %. (Rounded off to 2 decimal places)

The pitch of a metric screw thread is calculated from pitch circle diameter measurement through two-wire method. If the thread is single-start with calculated pitch of 1.4 mm then the diameter (in mm) of the best-wire is ______ . (Rounded off to 2 decimal places)

In an assembly comprising shaft and hole, the nominal sizes with tolerances are specified as

Hole: \(25.000^{+0.002}_{-0.001}\) mm,
Shaft: \(25.000^{+0.001}_{-0.003}\) mm.

The type of fit is

In a manufacturing system, four different types of products (P, Q, R and S) are produced. The batch size of each product is \(2 \times 10^{7}\). The numbers of defective units are 60, 71, 80 and 55, for P, Q, R and S, respectively. Which one of the following statements is TRUE?

In a factory, 100 bulbs are in use. The table lists the cumulative probability of the failure of a bulb for various durations. \[ \begin{array}{|c|c|} \hline \text{Duration (month)} & \text{Cumulative probability} \\ \hline 1 & 0.10 \\ 2 & 0.25 \\ 3 & 0.47 \\ 4 & 0.68 \\ 5 & 1.00 \\ \hline \end{array} \] The factory follows the individual replacement policy. If the cost of replacing a bulb is ₹300, then the expected cost (in ₹) of replacement per month is \(\underline{\hspace{2cm}}\). [round off to nearest integer]