Quantitative Aptitude - Arithmetic Ability Questions

Which of the following is correct?

What is the value of (cos 45 - 1/3) ?

Sum of a fraction and thrice of its reciprocal is 73/20. What is the fraction?

x, y and z are real numbers. If x3 + y3 + z3 = 13, x + y + z = 1 and xyz = 1, then what is the value of xy + yz + zx?

Select the odd word/letters/number/number pair from the given alternatives.

Select the odd letters from the given alternatives.

The HCF of 24, 60 and 90 is:

In a triangle PQR, ∠Q = 90°. If PQ = 12 cm and QR = 5 cm, then what is the radius (in cm) of the circum circle of the triangle?