Hello lukebushnell
The first one is:
$\displaystyle \dfrac{ds}{dt}= -15e^{-1.5t}$When $\displaystyle t=0.7$
$\displaystyle \dfrac{ds}{dt}= -15e^{-1.05}$
$\displaystyle =-5.25$, correct to 3 s.f.
The second one is correct to 2 s.f. ($\displaystyle 2.21$ to 3 s.f.)
Grandad
hi , thanks for the quick reply,. sorry about the equation the bit befoere the = sgn should be i , because the answer is electrical current, and as for the first one im not sure on the answer, i cant rmeber from the exam. i thnik ill just have to wait to august to find out, but thanks for the reply , i appreciate it