$8$

$2$

S

r

t

$=$

$0$

$4$

$.$

$5$

$0$

$\backslash$times

$1$

$0$

$8$

B

q

$.$

$$Calculate the number

o

f

$$nuclei that will decay

i

n

$$the time interval between

t

$1$

$=$

$4$

$0$

$.$

$0$

$$hours and

t

$2$

$=$

$7$

$5$

$.$

$0$

$$hours$.$

nuclei