Answer:
Step-by-step explanation:
If all 21 coins were dimes, she'd have $2.10. But she has 90 more cents than that. Now for each coin that's a quarter, not a dime, she has 15 cents more. 90/15= 6. So there are 6 quarters, and 21-6 = 15 dimes.
Now we do it backwards to see if it's right. 6 quarters is $1.50, 15 dimes is $1.50, add those together and you get $3. So it's right. 6 quarters, 15 dimes.
Answer:
tons of high steel and 
tons of low steel
Step-by-step explanation:
Let x be the number of tons of high grade steel and y be the number of tons ow low grade steel needed.
In x tons of high grade steel there are
tons of iron
tons of magnese
In y tons of low grade steel there are
tons of iron
tons of magnese
NASA orders 500 tons of steel, so
and specifies that it must be in the proportion 80% iron and 20% magnese, so
From the first equation,
Substitute it into the second equation:
The number of people in the sample survey is 75.
Survey sampling, as used in statistics, is the process of choosing a sample of constituents from a target population to perform a survey. The word "survey" can be used to describe a wide range of observational methods or procedures. Most frequently, a questionnaire meant to assess people's traits and/or opinions is employed in survey sampling. The topic of survey data collecting involves various methods of contacting sample participants after they have been chosen. Sampling is done to cut down on the expense and/or labor required to survey the complete target population. A census is a survey that includes all members of the target population. A sample is a subset or segment of a population from which data will be drawn.
The sample survey has
5 people in 1-4 miles per week
10 people in 5-8 miles per week
15 people in 9-12 miles per week
20 people in 13-15 miles per week
25 people in 16-19 miles per week
The number of people in the sample survey is
5 + 10 + 15 + 20 + 25
=5(1 + 2 + 3 + 4 + 5)
=5(15)
=75
Hence, the number of people in the sample survey is 75.
Learn more about sampling survey here-
brainly.com/question/24564273
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Answer:
Step-by-step explanation:
-4
Answer:
x=-0.5
Step-by-step explanation:
the question is -9=18x
we divide both sides by 9
-1=2x
divide both sides by 2
x=-0.5
