i'm solving electronic homework ,and i got the values R1=66.67
R2=12.4k
(and Rs=10 ,RL=1k are given),there is part in the question which want me to chose the closet values for the resistor before i design the circuit in pspice program.
can u tell me how i can chose from the given appendix below

Preferred resistance values (approximately 10% increase)

I1.01.52.23.34.76.8
II1.11.62.43.65.17.5
III1.21.82.73.95.68.2
IV1.32.03.04.36.29.1

I to IV for (+-)5% tolerance resistors
I and III for (+-)10% tolerance resistors
I for (+-)20% tolerance resistors

Values multiplied by 1, 10, 100, 1k, 10k, 100k, 1M, 10M
Multiplier 10 to 100k can cover all the preferred values
E.g. 11, 110, 1.1k, 11k, 110k

Resistor types: Carbon film, metal film, wirewound
i think this will be clear

I(1.0)(1.5)(2.2)(3.3)(4.7)6.8)
II(1.1)(1.6)(2.4)(3.6)(5.1)(7.5)
III(1.2)(1.8)(2.7(3.9)(5.6)(8.2)
IV(1.3)(2.0)(3.0)(4.3)(6.2)(9.1)

Hey there I am working on a project for guitar amplifier. So project requires 25-0-25 step down transformer. What is this. I mean how will it output voltage. Would 25+ and -25, +25 and 0 or something that will result total pd of 25. Well testing my circuit in software simulation so i required help for it..I am beginner in electronic (Science student of A-levels).

Here is the description of project regarding transformers. I am bit confuse about output 25-0-25 transformer but +/-35 output.?

The amplifier is designed for a maximum loaded supply voltage of +/-35V, and this must not be exceeded. Normal tolerance for mains variations is +/-10%, and this is allowed for. The transformer must be rated for a nominal 25-0-25 volt output, and no more.