Range of resistances?

Question

A resistor with a tolerance of 5% has a nominal value of 2.2kohms at room temp (20 deg celcius) it is rated at 2500 PPM/deg celc. find the range of resistances expected at 90 deg celc


the notes for this question that are supposed to tell me how to do it say The normal range is 2090 to 2310. Add 17.5% to each...

where did 17.5% come from

Answer 1

dT = 90-20 = 70 degC

2500 ppm/degC * 70 degC = 175000 ppm = 17.5%

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