Staals half
1 gram left
0.3 grams left
half lives are normally written in years
it goes likt this

A=final amount
P=initila amount
t=time elapsed
h=time half life is (same units as time)
let's use days as the units of time
we are given
initial amount=1gram
final amount=0.3gram
time=4 days
so

solve for h

take the ln of both sides


times both sides by h

divide both sides by ln(0.3)

use calculator
h=2.30287
3 sig figs
h=2.303 days
Answer:
72 grams
Step-by-step explanation:
7.2 x 10 = 72
Answer:
2⋅2⋅2⋅5=40 2 ⋅ 2 ⋅ 2 ⋅ 5 = 40
you can only choose 4 unique ways Step-by-step explanation:
Answer:
18 and 9
OR
-18 and -9
Step-by-step explanation:
Let:
first number = x
second number = y
According to given conditions:
x - y = 9 ---------- eq1
x * y = 162 ------- eq2
From eq1:
x = 9 + y
Put it in eq2:
(9+ y)*y = 162
9y + y^2 - 162 = 0
OR
y^2 + 9y -162 = 0
By factorizing we get:
y^2 -9y + 18y - 162 = 0
Taking common:
y(y - 9) + 18(y - 9) = 0
(y - 9)(y + 18) = 0
So:
y = -18 and y = 9
ignoring negative integer
Putting values of y in eq1:
x - 9 = 9
x = 9 + 9
x = 18
So the two numbers are:
18 and 9
OR
-18 and -9
i hope it will help you!