Below are sets of consecutive intervals from frequency distributions for continuous variables. For the second interval in each set, the one in bold, tell the real lower limit; the real upper limit; the interval width, i; and the interval midpoint, m.

a. 15–19; 20–24; 25–29

b. 205–245; 255–295; 305–345

c. 1.1–1.2; 1.3–1.4; 1.5–1.6

d. 1,000–2,000; 3,000–4,000; 5,000–6,000