How much pure alcohol must a nurse add to 10 cm3 of a 60% alcohol solution to strengthen it to a 90% solution?

30cm³

Step-by-step explanation:

6 + x = 9 + 0.9

0.1x = 3

0.1x ÷ 0.1 = 3 ÷ 0.1

x = 30

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.