The dot plots show the number of that each two sisters practiced the piano each day for 14 days.

The answer is in the image 

For every 8 cars there are 7 trucks

Therefore,

Cars:Truck=8:7

Answer is B)8:7

The solution is in the following image

y=2x+15

where y=Value of coin

x=Age in years

Value of coin after 19 years=2*19+15

=$53

Therefore, Value after 19 years=$53

The answer is in the image 

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

30% of 420 are first year students

first year students = (30/100 )*420

=126 students

Student who are not in first year = 420-126

=294 students  

There are 6 outcomes 1,2,3,4,5,6

Total outcomes = 6

Outcomes when rolling a number is 4 or less = 1,2,3,4

Total outcome when rolling a number is 4 or less=4

Probability = required outcome/total outcome

                 =4/6

                 =2/3

Therefore probability = 2/3

III is the case of joint variation as Area A depends on l and w

In I and II it depends on s and r respectively as pi is constant

Volume of pool = 1472 m^3

Length = 36.8m

Breadth = 20m

We know,

Volume = l*b*h

1472 = 36.8 * 20 * h

h = 1472/736

h = 2m

Pool is 2m deep