BitTech Pte Ltd $($BitTech$),$ with headquarters in Singapore, operates a computer server farm in

Texas, USA. It has some $4,000$ servers mining Bitcoin cryptocurrency. However, with Bitcoin

values fluctuating wildly, intense competition and increasing operating costs, the company has

decided to pivot its business to cloud services and to relocate its servers to Asia.

Table $1$ below shows technical data over the last $6$ months in $4$ countries that BitTech is

evaluating for the suitability of migrating its servers.

Table $1.$ Technical Data for Server Operation in $4$ Countries

The table above shows the electrical voltages that the power supply companies in the various

countries can provide. Availability indicates how many hours in a month where there is no

power outage. BitTech works on the basis of $365$ days a year over $12$ months. Some fluctuations

in voltage values and availability days are normal. The table shows measured values over a $6-$

month period.

The servers are sensitive electrical equipment and require stable power from the data centre

that houses the servers. To operate reliably, the data centres used by BitTech must be rated at

$22$ kV with a tolerance of $6\%.$

As an example, consider a data centre that is rated at $10$ kV with a tolerance of $10\%.$ This

means that it can only operate the servers if the power supplied varies between $9$ kV and $11$ kV

with a long$-$term average of $10$ kV$.$

BitTech also noted that the electricity rates in Indonesia, Malaysia, Singapore and Vietnam are

$$0\mathrm{.}16,$ $$0\mathrm{.}14,$ $$0\mathrm{.}25$ and $$0\mathrm{.}15$ per kWh$,$ respectively. These rates are expected to remain

relatively unchanged for the foreseeable future.

BitTech prides itself of its ability to provide services at a guaranteed availability of at least

$99\mathrm{.}95\%.$ For added assurances, it also requires the power suppliers to match this level of

availability.

In the industry, the Percentage Availability metric is defined as System Available Hours $/$ Total

Calendar Hours expressed as a percentage. Thus, if a system is available for service for $657$

hours in a month, the Percentage Availability would be computed as $90\%$ per month.

$[$Hint: $90\%=0\mathrm{.}90=657$ hours $/(24$ hours x $365$ days $/12$ months$)]$

$($a$)$ You are required to develop appropriate models to analyse the questions that follow.

Your answers must be justified quantitatively. All such models must contain formulae

and functions. Hardcoding is not allowed.

$($i$)$ Which countr$($ies$)$ are not technically feasible for the migration of the servers?

Explain, with reference to your model, why these countr$($ies$)$ are not suitable.

$($ii$)$ Show, using your model, which countr$($ies$)$ are potentially suitable. Identify the

most ideal country. Justify why.

$($iii$)$ The CTO of BitTech suspects that there are errors in some of the availability

hours for Vietnam in Table $1.$ The affected values are all misstated by the same

$$X$$ number of hours. The long$-$term availability should be $99\mathrm{.}99\%.$ Using

Solver or otherwise, show which values are incorrect and state the value of $$X$.$

Explain how you derive your answer.

Help to construct an excel model based on the information given above.