I believe it's 3/10 but I'm not confident about that.
The area of a circle in terms of the circle's radius

is

Differentiating both sides with respect to

, you get
From the given question we come to know of certain number of facts and they are:
At 1:00 PM the water level of the pond was = 13 inches
At 1:30 PM the water level of the pond was = 18 inches
At 2:30 PM the water level of the pond was = 28 inches
From the above given facts we can easily find the amount of water changing every half an hour.
Amount of increase in water from 1:00PM to 1:30 PM = (18 - 13) inches
= 5 inches
Amount of increase in water level from 1:30PM to 2:30PM = (28 -18) inches
= 10 inches
From the above two deductions we can come to the conclusion the the constant rate of change in water level is 5 inches for every half an hour.
Answer:
The table representing the number of students by which mode of transport they travel is given as:
Walk or bike Bus Car Row Total
Below age 15 87 60 18 165
Age 15 and above 65 50 80 195
Column Total 152 110 98 360
We know that a relative frequency of an event is the ratio of frequency to the total number of trials.
i..e we divide each frequencies by 360 to obtain a two-way relative frequency.
Hence,the table is given as:
Walk or bike Bus Car Row Total
Below age 15 0.24 0.17 0.05 0.46
Age 15 and above 0.18 0.14 0.22 0.54
Column Total 0.42 0.31 0.27 1