If an ostrich can run 50 miles in one hour then he can run 12.5 miles in 15 minutes. 15 minutes is 1/4 of an hour. Multiply 50 by 0.25 = 15.
Answer:
20 mph
Step-by-step explanation:
First problem:
The new speed is 26 mph.
The old speed was x.
The new speed is 30% higher than the old speed.
1.3x = 26
x = 20
Answer: 20 mph
Second problem:
A number, perhaps a percent or a fraction, is missing from the problem.
Given is the number of science fiction books = 48
Let the number of mystery books be = x
Let the number of biographies be = y
Ratio of the number of mystery books to the number of science fiction books is 4:3 so
=

Ratio of the number of science fiction books to the number of biographies is 4:5 so 
=

Hence there are 48 science fiction books, 64 mystery books and 60 biographies.
So total number of books are = 
Answer:
The question should say..... How much of the sample is left in......FIVE.....weeks? At least that is what I think you want to know.
The answer is 318.13 grams.
Step-by-step explanation:
450 - 6.7% = 419.85 grams ---- End of week 1
419.85 - 6.7% = 391.72 grams ---- End of week 2
391.72 - 6.7% = 365.47 grams ---- End of week 3
365.47 - 6.7% = 340.98 grams ---- End of week 4
340.98 - 6.7% = 318.13 grams ------ End of week 5
12 divided by 4 squared is 12 divided by 2 which is 6