Answer:
2 2/3 teaspoons
Step-by-step explanation:
When scaling a recipe up or down, we like to keep the same proportions of ingredients. The proportion can be written ...
x/(1/2) = (4)/(3/4) . . . . . larger recipe/smaller recipe
x = (1/2)(16/3) = 8/3 . . . teaspoons salt
The amount of salt needed is 2 2/3 teaspoons.
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Additional comment:
We have chosen to write the proportion above in terms of ratios of same ingredients. You can also write the proportion in terms of different ingredients:
(1/2 tsp salt) : (3/4 c sugar) = (1/2)/(3/4) tsp/cup = 2/3 tsp/cup
where the tsp is the measure of salt, and cup is the measure of sugar. Then for 4 cups sugar, you need ...
(2/3 tsp/cup)(4 cups) = 8/3 tsp . . . of salt
