Let's handle this case by case.
Clearly, there's no way both children can be girls. There are then two cases:
Case 1: Two boys. In this case, we have 13 possibilities: the first is born on a Tuesday and the second is not (that's 6 possibilities, six ways to choose the day for the second boy), the first is not born on a Tuesday and the second is (6 more possibilities, same logic), and both are born on a Tuesday (1 final possibility), for a total of 13 possibilities with this case.
Case 2: A boy and a girl. In this case, there are 14 possibilities: The first is a boy born on a Tuesday and the second is a girl born on any day (7 possibilities, again choosing the day of the week. We are counting possibilities by days of the week, so we must be consistent here.), or the first is a girl born any day and the second is a boy born on a Tuesday (7 possibilities).
We're trying to find the probability of case 1 occurring given that case 1 or case 2 occurs. As there's 13+14=27 ways for either case to occur, we have a 13/27 probability that case 1 is the one that occurred.
Let x be the volume (liters) of pure (at 100%) acid needed
Let y be the volume (liters) of the other acid (at 10%) needed
The final solution will be:
a) x+ y = 63 liters, AND their respective concentration in acid: is
100% x & 10% :y that will generate 63 liters at 20%
b) x +0.1 y = 63x 0.2 = 12.6
Let's solve this system of 2 equations:
x + y =63
x + 0.1 y = 12.6
Solving it will give you:
x= 7 liters at 100%
y = 56 liters at 10%
The temperature started at 15 degrees.
It dropped 25 degrees.
Subtract 25 from 15:
15 - 25 = -10
The temperature was -10 degrees.
Answer:
c 18
Step-by-step explanation:
Idid thsi in Kahn academy and got it correctly
