Answer:
56 days
Explanation:

where A is final amount, Ao is initial amount, t is time taken, h is half life
Here given:
initial amount: 400 millicuries
final amount: 3.125 millicuries
half life: 8 days
time taken: ?
Hence solve for time taken:

<u>insert values given</u>

<u>divide both sides by 400</u>

<u>apply exponent rule</u>
<u />
<u>simplify</u>

<u>multiply both sides by 8</u>

Answer:
Restaurant A is a better deal because you get more amount of money and for restaurant b you don't know how much they are tipping.
Step-by-step explanation:
I got 12 hours and 31 minutes.
Step-by-step explanation:
Total marbles = 10
No of white marbles = 4
No of blue marbles = 6
Probability of 2 white marbles = 4/ 10 = 2/5