Use this formula:
K = K_0 * (1+r)^n
Insert and solve for n:
12600 = 6000 * (1+0.065)^n
n = 11.78
So about 12 quarters.
Hope that helped.
Writing the equation that governs this situation:
-3C - (2.5C/hr)x = -18C
Simplifying, -3 - 2.5x = -18, or 3 + 2.5x = 18
Combining like terms: 2.5x = 18-3 = 15
Then x = 15/2.5 = 6. The temp. will reach -18C after 6 hours.
Assuming the keypad has all 26 letters and the numbers 1-9 there are 2106 possible codes
9x9x26=2106
The probability is 7/10 because there are only 7 boys or it could be 70%
