Answer:
12
Step-by-step explanation:
The general formula for this is
Formula
1/t1 + 1/t2 = 1/t_tot
givens
t1 = 6 hours
t2 = x
t_tot = 4 hours
Solution
1/6 + 1/x = 1/4 Subtract 1/6 from both sides.
1/6-1/6 + 1/x = 1/4 - 1/6 Change to 12 as your common denominator
1/x = 3/12 - 2/12 subtract
1/x = 1/12 Cross multiply
x = 12
Tom would need 12 hours to do the job alone.
Answer: 7
Step-by-step explanation:
For c, we are given this sum from 1 to 3 of 
. 1/2 is a constant , therefore, we can move it outside of the summation.
*I hope you can understand what I'm saying. I can't figure out how to type in summations into the equations section.
1/2∑₁³n²
This means you would multiply the sum of n² from 1 to 3 by 1/2.
We are told n=1 to n=3 so we would plug 1, 2, 3 into n.
1²=1
2²=4
3²=9
We would add them together since that is what the sum sign tells us to do.
1+4+9=14
Now that we know the sum, we multiply it with 1/2
14/2=7
Answer:
2 grams
Step-by-step explanation:
50 years is 5 half lives as 1 half life is 10 years.
64 divide 2 = 32-1 half life
32 divide 2 =16-2nd half life
16 divide 2 = 8-3rd half life
8 divide 2 = 4-4th half life
4 divide 2 = 2-5th half life
This means we will have 2 grams left of the radioactive substance after 50 years.
I got you. The answer would be A (Certificate)
