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On the Celsius scale the temperature of a body increases by 40 °C. The increase in temperature on the Fahrenheit scale is

Asked in JEE Main 4th April 1st Shift 2024 · Temperature scales

• (1) 68 °F
• (2) 72 °F
• (3) 70 °F
• (4) 75 °F

Step-by-step solution

Why the other options are wrong

• (1) 68 °F is the Fahrenheit reading that corresponds to 20 °C, picked from memory of the conversion table rather than computed; no route from a 40 °C rise gives it. The usual slip, adding the 32 to a difference, gives 9/5(40)+32=104, which is not offered.
• (3) comes from rounding 9/5=1.8 down to 1.75 and getting 40×1.75=70; the ratio of interval sizes is exactly (180)/(100), with no rounding needed.
• (4) comes from no consistent slip lands here; it is a filler placed just above the key. Reading the ratio as (15)/8 would give it, but that ratio comes from nowhere in the two scales.

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