Question

i can solve problems using data represented in dot plots.

1. a pediatricians office tracks the age (in months) in which 25 babies begin to walk. use the

dot plot at the right to answer the questions below.
babies begin walking
a. how many babies begin walking before 13 months of age?
b. what percent of babies begin walking at 12 months?
c. which three ages combined account for less than 16% of the babies?

Explanation:

Step1: Count babies before 13 months

Count dots for ages 9, 10, 11, 12. There is 1 dot at 9, 1 at 10, 3 at 11, 7 at 12. So \(1 + 1+3 + 7=12\).

Step2: Calculate percentage for 12 months

There are 7 dots at 12 months. Total babies \(n = 25\). Percentage \(P=\frac{7}{25}\times100\% = 28\%\).

Step3: Find ages for less than 16%

16% of 25 is \(0.16\times25 = 4\). Check combinations. Ages 15 (2), 16 (2), 17 (1). \(2 + 2+1=5>4\). Ages 14 (3), 16 (2), 17 (1). \(3 + 2+1 = 6>4\). Ages 9 (1), 10 (1), 17 (1). \(1+1 + 1=3<4\).

Answer:

a. \(12\)
b. \(28\%\)
c. \(9\), \(10\), \(17\)