Answer:
1.) 8.09g ; 2) 206.7 years
Step-by-step explanation:
Given the following :
Half-life(t1/2) of Uranium-232 = 68.9 years
a) If you have a 100 gram sample, how much would be left after 250 years?
Initial quantity (No) = 100g
Time elapsed (t) = 250 years
Find the quantity of substance remaining (N(t))
Recall :
N(t) = No(0.5)^(t/t1/2)
N(250) = 100(0.5)^(250/68.9)
N(250) = 100(0.5)^3.6284470
N(250) = 100 × 0.0808590
= 8.0859045
= 8.09g
2) If you have a 100 gram sample, how long would it take for there to be 12.5 grams remaining?
Using the relation :
N / No = (1/2)^n
Where N = Amount of remaining or left
No = Original quantity
n = number of half-lifes
N = 12.5g ; No = 100g
12.5 / 100 = (1/2)^n
0.125 = (1/2)^n
Converting 0.125 to fraction
(1/8) = 1/2^n
8 = 2^n
2^3 = 2^n
n = 3
Recall ;
Number of half life's (n) = t / t1/2
t = time elapsed ; t1/2 = half life
3 = t / 68.9
t = 3 × 68.9
t = 206.7 years
Answer:
The mass of a longhorn cow.
Step-by-step explanation:
Kilograms will measure mass, not length, so we are left between two options. Kilograms would be used for heavier objects, so between a paper clip (which would be likely measured in grams,) and the longhorn, the cow would be what you would measure in kilograms.
Answer: 15
Step-by-step explanation:
Given : Level of confidence = 0.90
Significance level :
Critical value :
Margin of error :
Standard deviation:
The formula to find the sample size :
Hence, the minimum sample size needed= 15.
Answer:
the table which is the second choice
Step-by-step explanation:
Option A:
1.5 lb bag for $12.99
unit price: $12.99/(1.5 lb) = $8.66/lb
Option B:
unit price: $2.8/(0.2 lb) = $14/lb
Option C:
For the weight of 1 lb, the cost is $10.
unit price: $10/lb
Answer:
the table which is the second choice
Answer:
The answer for the problem would be -12
Step-by-step explanation:
(28+35) = 63
63-75= -12