8+11=19 but if you add 21+19+12+5=57.
Hello there! A half-life is basically a decay of 50%. We will find the amount left after one day by exponential decay. The formula for exponential decay is A(1 - r)^t, where A = initial amount, r = rate (in decimal form), and t = time (or in this case, amount of half lives). The half-life is 6 hours and 24 goes into 6 four times. That's 4 half lives. Let's start by subtract 50% (0.5) from 1. 1 - 0.5 is 0.5. Now, we will use 0.5 and raise it to the 4th power, because the 4th power represents 4 half lives. 0.5^4 is 0.0625. Leave this number on the calculator. Do not round. Multiply that number by 448 to find the amount left. When you do, you get 28. There. 28 grams will be left after 24 hours.
Redued by 15%
orignal=100%
decrease by 15%=100%-15%=85%
find 85% of original
orignal=15 feet
85% of 15=0.85 times 15=12.75 feet
answer is B
Answer:

Step-by-step explanation:
3 envelopes having 2 red card
2 envelopes having 1 red card and 1 black card
1 envelope having 2 black cards
We are given that . An envelope is selected at random and a card is withdrawn and found to be red.
So, No. of ways of envelope having red card = 3+2 = 5
No. of required ways of envelope having 1 red card and 1 black card = 2
So, probability of getting an envelope having 1 red card and 1 black card = 
Hence The chance the other card is black is 
When you write an equation in the slope-intercept form

the two coefficients m and b represent, respectively, the slope and the intercept.
So, in your case, m=1/4 and b= -7, which leads to the equation
