$(1$ point$)$

If the current i$($t$)$i$($t$)$ for an element is $1\mathrm{.}2$t$1\mathrm{.}2$t A for t$0$t$0,$ and $10$t$10$t A for t$0$t$0.$

Find:

$($a$)$ i$(6\mathrm{.}9)$i$(6\mathrm{.}9)$

$($b$)$ i$(8\mathrm{.}4)$i$(8\mathrm{.}4)$

$($c$)$ The total charge that has passed through the element in the interval $6\mathrm{.}9$t$8\mathrm{.}46\mathrm{.}9$t$8\mathrm{.}4$

$($d$)$ The average current that has passed through the element in the interval $6\mathrm{.}9$t$8\mathrm{.}46\mathrm{.}9$t$8\mathrm{.}4.$

$($a$)$ : A

$($b$)$ : A

$($c$)$ : Coul.

$($d$)$ : A