It’s 10.5 I’m pretty sure
There are three groups of people: 25 years old and younger, between 25 to 50, and 50 years old and older. Their fractions must equal to 1 because these three together form the whole.
1 = 1/3 + 2/7 + x
where x is the fraction for people ages 25 to 50 years old
x = 8/21
So, the actual number of people ages 25 to 50 years old is:
84(8/21) = 32 people
Answer:
the second one
Step-by-step explanation:
i did it in my head and double checked :)
The figure on the left side shows the water level is at the 0.5 liter mark, ie half a liter.
1 liter = 1000 mL
0.5*1 liter = 0.5*1000 mL
0.5 liter = 500 mL
If you poured all the water into the jug on the right (without spilling), then the water level should reach the 500 mL mark. This is the small tickmark exactly halfway between the 400 and 600.
1). Multiply (5400 inches) by (1 foot / 12 inch) then by (1 mile / 5280 foot).
(See explanation at the bottom)
= (5400 inch) x (1 foot / 12 inch) x (1 mile / 5280 foot)
= (5400 x 1 x 1 / 12 x 5280) (inch - foot - mile / inch - foot)
= 0.0852 mile
2). Multiply (16 week) by (7 day/week) then by (24 hour/day)
then by (60 minute/hour) then by (60 sec/minute).
3). Multiply (54 yards) by (3 foot/yard) then by (1 meter/3.28 foot)
and then by (1000 mm/meter)
4). Multiply (36 cm/second) by (3600 second/hour) then by (1 meter/100 cm)
then by (1 mile/1609.3 meter).
5). Look up how many grams in a pound ('P')
Look up how many mL in a gallon ('G')
Multiply (1.09 g/mL) by ( 1 pound/ P gram) then by (1 gallon/ G mL)
6). Multiply (32 foot/sec) by (1 meter / 3.28 foot) then by (60 sec/minute).
Each time I told you to multiply by something, it was always a fraction
where the numerator and denominator are equal, like (60 seconds/minute)
or (1 foot / 12 inch). Since the top and bottom of the fraction are equal, the
value of the fraction is ' 1 ' , and multiplying by it doesn't change the value,
it only changes the units ... that's what this whole exercise is about.
When you multiply, KEEP the units in the product, and then, after you multiply, you can 'cancel' units out of the top and bottom of the product.
Like if you have 'feet' on top and bottom, just cross them out. When you're done, if you did it correctly, the last unit you end up with will be the one you want.
