Basic Mathematics for College Students

78. RAMPS Write a ratio of the rise to the run for
    each ramp shown. Set the ratios equal.
    a. Is the resulting proportion true?
    b. Is one ramp steeper than the other?


79. MIXING PERFUMES A perfume is to be mixed in
    the ratio of 3 drops of pure essence to 7 drops of
    alcohol. How many drops of pure essence should be
    mixed with 56 drops of alcohol?


80. MAKING COLOGNE A cologne can be made by
    mixing 2 drops of pure essence with 5 drops of
    distilled water. How much water should be used with
    15 drops of pure essence?


81. LAB WORK In a red blood cell count, a drop of the
    patient’s diluted blood is placed on a grid like that
    shown below. Instead of counting each and every red
    blood cell in the 25-square grid, a technician counts
    only the number of cells in the five highlighted
    squares. Then he or she uses a proportion to estimate
    the total red blood cell count. If there are 195 red
    blood cells in the blue squares, about how many red
    blood cells are in the entire grid?


82. DOSAGES The proper dosage of a certain
    medication for a 30-pound child is shown. At this rate,
    what would be the dosage for a 45-pound child?

1/8 OZ

1/4 OZ

1/2 OZ

3/4 OZ

1 OZ

Run 20 ft Run 30 ft

Rise

12 ft

Rise

18 ft

83. DRAFTING In a scale drawing, a 280-foot
    antenna tower is drawn 7 inches high. The building
    next to it is drawn 2 inches high. How tall is the
    actual building?


84. BLUEPRINTS The scale for the drawing in the
    blueprint tells the reader that a -inch length on
    the drawing corresponds to an actual size of 1 foot
    ( ). Suppose the length of the kitchen is inches
    on the blueprint. How long is the actual kitchen?


85. MODEL RAILROADS An HO-scale model
    railroad engine is 9 inches long. If HO scale is
    87 feet to 1 foot, how long is a real engine?
    (Hint:Compare feet to inches. How many inches
    are in one foot?)


86. MODEL RAILROADS An N-scale model
    railroad caboose is 4 inches long. If N scale is
    169 feet to 1 foot, how long is a real caboose?
    (Hint:Compare feet to inches. How many inches
    are in one foot?)


87. CAROUSELS The ratio in the illustration below
    indicates that 1 inch on the model carousel is
    equivalent to 160 inches on the actual carousel.
    How wide should the model be if the actual
    carousel is 35 feet wide? (Hint:Convert 35 feet
    to inches.)

?

Carousel ratio

1:160

KITCHEN BEDROOM

BEDROOM

SCALE: = 1'-0"

LIVING ROOM

BATH

HEAT RM

1 "–

4

1  (^0 2 12)
(^14114 2)
5.2 Proportions 441