A closed box is constructed of 4200cm2 of cardboard. The box is a cuboid, with height hcm and square base of side xcm . What is the value of x which maximises the volume of the box? Give your answer in cm correct to 3 significant figures. [Answer format: 00.0 cm]

x is 10

Step-by-step explanation:

Given that:

<=> 2 + 4xh = 4200 cm2

<=> 4xh = 4200 - 2  

<=> h = (4200 - 2  )/4x

V =  h

<=> V =  (4200 - 2  )/4x

<=> V = (4200x - 2 )/4

dV/dx = (4200 - 6 )/4

Set dV/dx = 0, we have:

4200 - 6 =0

<=>  = 700

<=> x = 10

d²V/dx² =  -12x/4

It is negative so the volume is maximum.

So x is 10

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26 is 33.33% of 78

step-by-step explanation:

26 is what percent of 78?

26 is p% of 78

equation: y = p% * x

solving our equation for p

p% = y/x

p% = 26/78

p = 0.3333

convert decimal to percent:

p% = 0.3333 * 100 = 33.33%