Answer:
9:1
Step-by-step explanation:
90:10
find number both can be divided by(simplify)
90/10 10/10
9:1
where A=final amount
P=principal
r=rate in decimal form
t=time in years
we are given that P=500, r=12%=0.12
we want to find A when t=10, 20, and 30
so
when t=10, 
when t=20, 
when t=30, 
We observe that 20 is 4 more than twice 8. This suggests the time is 1 hour and the rates are
... scooter: 20 mi/h
... bicycle: 8 mi/h
_____
You can let b represent the rate of the bicycle in miles per hour. Then we have (for time in hours and distance in miles) ...
... time = distance/speed
... time = 20/(2b+4) = 8/b
... 20b = 8(2b+4) = 16b +32
... 4b = 32
... b = 8
The rate of the bicycle is 8 mph; that of the scooter is 2*8+4 = 20 mph.
D. Apple’s market share fell about 4% from 2012 to 2013.
Gauss's approach is to add the same sequence in reverse order, namely
S=1+3+5+7+......+95+97+99
S=99+97+95+......+7+5+3+1
---------------------------------------
2S=(1+99)+(3+97)+(5+95)+......(95+5)+(97+3)+(99+1)=50*100=5000
=> sum = (2S)/2 = 5000/2=2500.
