Question

what method will you adopt to measure the volume of banana

Answer 1

Volume of a 
Banana
:
Integration-Style
Plug both equations into the "Y=" tab and graph them to make sure they are accurate
Peel the banana. Cut it in half, lengthwise
On graph paper, label the x and y axes, trace one slice of the banana on it.
Notice that the graph shows 2 quartic curves
Go to the STAT button on the graphing calculator and plug in the X and Y coordinates for both curves
Measure 400 mL of water in a measuring container. Place full banana in the container and record the rise in volume of water.
Find all of the direct points on the graph of the banana
For each curve go to STAT, CALC, and go to QuartReg. Find the quartic function for each curve. You would use the quartic regression for both curves because the bottom one has a "w" shape indicating that it is quartic. The top curve is not exactly a parabola, so quartic would also be used for it, to be safe.
Go to 2nd, TRACE and go to 
intersect
and find out the 2 intersecting points for both curves.
This would be a cross-section graph because it is a 3D solid with 2 different curves. Each slice of the banana is a circle, so the formula for the cross-section of the diameter of the circle would be: 
Volume of banana (water displacement):
about 110 mL
= 107.053 cm^3
Calculations
Summary
I peeled the banana and cut it in half, lengthwise. On graph paper, i then labeled the x and y axes, and traced one slice of the banana on it. I measured 400 mL of water in a measuring container and placed the full banana in the container and recorded the rise in volume of water. This is the volume of the banana, which came to be about 110 mL or cm^3. I found all of the direct points on the graph of the banana. I then noticed that the graph shows 2 quartic curves. I went to the STAT button on the graphing calculator and plugged in the X and Y coordinates for both curves. For each curve i went to STAT, CALC, and QuartReg. I found the quartic function for each curve. I used the quartic regression for both curves because the bottom one has a "w" shape indicating that it is quartic. The top curve is not exactly a parabola, so quartic would also be used for it, to be safe. I plugged both equations into the "Y=" tab and graphed them to make sure they are accurate. I then found the 2 intersecting points for both curves by going to 2nd, TRACE and go to 
intersect
. This would be a cross-section graph because it is a 3D solid with 2 different curves. Each slice of the banana is a circle, so the formula for the cross-section of the diameter of the circle would be: . 
Summary Continued...
For the calculations I figured out that for the top curve the equation g(x) would be Y1 in the calculator
For the bottom curve, the equation f(x) would be Y2 in the calculator. Then I began the integration. The a= -8.132 and b=7.57519. The "d^2" in the cross section formula is equal to the (top eqation - bottom equation)^2 which is equal to (Y1 - Y2)^2 in the calculator. This is all multiplied by (pi/4) dx. Once this was all plugged into the calculator, I had (pi/4)(136.3042167). Once that was simplified I had the volume of the banana by integration as 107.05308. For the units I used cm^3 which is equivalent to mL. The graph paper I used was especially imperative to this unit because each box or square was 1/2cm so I made each point 2 boxes long.

Answer 2

You can use any way. Example - of a cube, cuboid, and many more as you wish. Hope you have understood.