(a) Given Ragi flour:raw rice = 4 : 1
If one cup of ragi flour used then the ratio of ragi flour : raw rice = \(\frac { 4 }{ 4 } :\frac { 1 }{ 4 } =1:\frac { 1 }{ 4 } \)
Raw rice required = \(\frac { 1 }{ 4 } \) cup
(b) Ratio of water : ragi flour = 8 : 4
If 16 cups of water used then ratio of water : ragi flour = 8\(\times\)2 : 4\(\times\)2 = 16 : 8.
So, 8 cups of ragi flour is used.
(c) We know that the quantities of same units can be compared. Here Ragi flour, Raw rice and water are in one unit, Sesame oil and salt are in different units, these different units cannot be compared and cannot be expressed as a ratio.

Number of green cubes = 3
Number of blue cubes = 9
Number of yellow cubes = 4
Number of orange cubes = 8
(a) Ratio of orange to yellow cubes = \(\frac { Number\ of\ orange\ cubes }{ Number\ of\ yellow\ cubes } \)
 =\(\frac { 8 }{ 4 } =\frac { 2 }{ 1 } \) = 2 : 1
Ratio of orange to yellow cubes = 2 : 1
(b) \(\frac { Number\ of\ green\ cubes }{ Number\ of\ blue\ cubes } =\frac { 3 }{ 9 } =\frac { 1 }{ 3 } \)
Ratio of green to blue cubes = 1 : 3
(c) The ratios can be Orange:
Yellow, Orange: blue, Orange: green, Yellow: orange, yellow: blue, yellow: green, blue: green, blue: orange, blue: yellow, green: orange, green: yellow, green: blue. Thus 12 ratios can be formed.
i.e., the possiblity of forming the different ratios
3 : 9, 3 : 4, 3 : 8
9 : 3, 9 : 4, 9 : 8
4 : 3, 4 : 9, 4 : 8
8 : 3, 8 : 9, 8 : 4

In my purchase cost of 6 apples = Rs. 90
∴ cost of 1 apple = \(\frac { 90 }{ 6 } \) = Rs. 15
In my friend's purchase cost of 5 apples = Rs. 70
∴ Cost of apple =\(\frac { 70 }{ 5 } \) = Rs. 14
My friend buy for lower prize.
∴ My friend's purchase is a better buy.

The ratio of Golden Gate Bridge & Its model are = 6480 : 756 and 60 : 7
Product of extremes = 6480 \(\times\) 7 = 45,360
Product of means = 756 \(\times\) 60 = 45,360
Product of extremes = Product of means
∴ The model is in proportion to the ordinal bridge.

Total length 63 cm, on dividing 3 + 4 = 7 equal parts, we get the line segments with lengths
\(\frac{3}{7}\times63=27\ cm\)
\(\frac{4}{7}\times63=36\ cm\)
Length of each line segment is 27 cm & 36 cm