Review: Scientific Calculator Skills

Evaluate:
 $25\ +36\ \div\left(24\%\ \times25\right)$  

What is fifty percent of the quotient of twenty-four and the sum of three and five?

Peter is 30 years old, his twin brothers are 23 years old and his twin sisters are 12 years old. What will the sum of their ages be in 4 years time?

Evaluate:

 $\frac{23}{12}-\frac{3}{17}$  
Expresss your answer in two decimal places.

Given the quadratic equation

 $x^2-5x+2=0$ , 
find its discriminant. 

Using the quadratic formula, find the root/s of the quadratic equation

 $y=4x^2-20x+25$  

Find the surface area of a sphere with radius = 6m.

Express your answer in two decimal places. No need to write the unit.

It's 2 hours 15 minutes past 5:30 PM. What time was it 30 minutes ago?