Answer:
Step-by-step explanation:
Question (1). An alloy contains zinc and copper in the ratio of 7 : 9.
If the weight of an alloy = x kgs
Then weight of copper = 
= 
And the weight of zinc = 
= 
If the weight of zinc = 31.5 kg
31.5 =
x = 
x = 72 kgs
Therefore, weight of copper = 
= 40.5 kgs
2). i). 2 : 3 = 
4 : 5 = 
Now we will equalize the denominators of each fraction to compare the ratios.
= 
Since, 
Therefore, 4 : 5 > 2 : 3
ii). 11 : 19 = 
19 : 21 = 
By equalizing denominators of the given fractions,
And 
Since, 
Therefore, 19 : 21 > 11 : 19
iii). 
= 
Now we equalize the denominators of the fractions,
And 
Since 
Therefore, 
will be the answer.
IV). 
Similarly, 
By equalizing the denominators,
Similarly, 
Since 
Therefore, 
V). If a : b = 6 : 5
And b : c = 10 : 9
Since a : b = 12 : 10
And b : c = 10 : 9
Since b = 10 is common in both the ratios,
Therefore, combined form of the ratios will be,
a : b : c = 12 : 10 : 9
$4.05/1.8 oz= $2.25 per oz
Final answer: $2.25 per oz
Answer:
See below
Step-by-step explanation:
You need to create an equation that will give you the results with the correct units of measurement that they are asking for. In the first question, they are asking you to give the answer in seconds. So when you set up your equation, seconds have to be on the top. The way to think of this is to actually reword the statement they give you by saying in 1 second, light travels 3 x 10 to the 8th power which is 3 with 8 zeros after it. Then it's easier to set up the equation as below. The distance from the Sun to Mars is 230,000,000,000 meters which is the same as saying 2300 x 10 to the 8th power. Notice I counted 8 of the zeros and used that in the exponent but left the rest as part of the original number. This will make it easier since you are dealing with two number that have exponents raised to the same power of 8.
1 sec 2300 x 10⁸ m
-------------- X -------------------- =
3 x 10⁸ m 1
When you look at this equation it looks difficult but since both the top number and bottom number are exponents raised to the same power, they cancel each other out. So you can drop the exponent all together and just divide the top number by the bottom number 2300 ÷ 3 which equals 766 seconds.
The second question needs you to take the distant the Sun is from Earth and subtract that from the distance from the Sun to Mars. By subtracting those two, it will tell you how far Mars is from the Earth. You can change the numbers a little bit to make it easier on you. Again you want the exponent for both numbers to be the same to make it easier. When you subtract two number with the exact same exponent, you can just subtract the number and then use that same exponent as part of your answer.
The distance between the Sun and Mars is 23 with 10 zeros after it. So that is the same as writing 23 x 10¹⁰. The distance from the Sun to Earth is said to be 1.5 x 10¹¹ but that is a different exponent. So if you move the decimal on this number one place to the right, it will be 15 x 10¹⁰. Now you can easily subtract those numbers without worrying about the exponent since they are the same.
23-15 =8 but now you have to put the exponent back on. So your answer ends up being
8 x 10¹⁰ or 8 with 10 zeros or 80,000,000,000 meters.
