Resistance array packages are particularly useful when the design constraints involve resistance ratios. The nominal resistance can change from one array to the next, but within a given array the resistances are all nearly equal, so their ratios are nearly unity. In effect, the resistance array in Figure 3-54 contains seven identical resistors, although we do not know the exact value of their resistance. Constructing the series leg using three resistors in parallel and the shunt leg using four resistors in parallel produces R1 R13 and R2 .R/4, where R is nominally 1 kn. But regardless of the actual value of R. the ratio R/R 1.33 as required.