$5\mathrm{.}13$ Mean time between failures $($MTBF$),$ mean time to replacement $($MTTR$),$

and mean time to failure $($MTTF$)$ are useful metrics for evaluating the reliability

and availability of a storage resource. Explore these concepts by answering the

questions about a device with the following metrics:

$5\mathrm{.}13\mathrm{.}1[5]$$$5\mathrm{.}5>$ Calculate the MTBF for such a device.

$5\mathrm{.}13\mathrm{.}2[5]$$$5\mathrm{.}5>$ Calculate the availability for such a device.

$5\mathrm{.}13\mathrm{.}3[5]$$$5\mathrm{.}5>$ What happens to availability as the MTTR approaches $0?$ Is

this a realistic situation?

What happens to availability as the MTTR gets very high, i$.$e$.,$

a device is difficult to repair? Does this imply the device has low availability?