complete the next $2$ questions:

$3.$ What was the forecast error for August?

a$.8\mathrm{.}3.$

b$.-12\mathrm{.}4$

c$.18\mathrm{.}2$

d$.-10\mathrm{.}1$

Month Sales

$1270$

$2310$

$3250$

$4290$

$5370$

$6410$

$7400$

$8450$

$9-$

Month Demand Forecast

Jan $120-$

Feb $110120\mathrm{.}0$

March $150116.$

April $130129\mathrm{.}6$

May $160129\mathrm{.}7$

June $165141\mathrm{.}8$

July $140151\mathrm{.}1$

Aug $155146\mathrm{.}7$

$4.$ What is the Tracking Signal $($TS$)$ for August?

a$.$

$1\mathrm{.}65$

b$.$

c$.$

$4\mathrm{.}48$

$3\mathrm{.}18$

d$.-4\mathrm{.}12$