There are 10,000 total four-digit numbers (1000 through 9999).
Multiples of 2 end in 0, 2, 4, 6, and 8. There are 9*10*10*5 = 4500 four-digit multiples of 2.
Multiples of 5 end in 0 or 5. There are 9*10*10*2 = 1800 four-digit multiples of 5.
There is redundancy between the two sets of numbers, namely those that end in 0, which are both multiples of 2 and 5. There are 9*10*10*1 = 900 four-digit multiples of both 2 and 5.
Then there are 4500 + 1800 - 900 = 5400 total four-digit numbers that are either multiples of 2 or 5, which means the remaining 4600 numbers are neither multiples of 2 nor 5.
Luis spent $9.50, in which:
Candy (y) = $1.25
Chips (x) = $0.50
$9.50 = 1.25y + 0.50x
Luis bought 10 snacks in all
10 = x + y
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You're answer:
x + y = 10
1.25y + 0.50x = 9.50
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hope this helps
Answer:
19
Step-by-step explanation:
In the first day the population will decrease to 1530, then 1500 the day 2, 1470 day 3, and so on ...
For decrease and get less than 1000 the mold population needs to be reduced in at least 560. The questions turns to be, how many days will it take to reduce the population in 560 spores?
If we divide 560 between 30 it will gives us the answer:
560/30 = 18.667
So, it is need to wait 19 days. In 18 days only 540 spores are reduced. In 19 days 570. We will say 19 days as we are looking (I guess) for an integer number.
