GIVEN:

R1 = 200 cGyph.

FIND:

Rt at H + 25 hours.

SOLUTION:

Connect 2000 cGyph (10 x 200 cGyph) on the R1 scale and 25 on

the index (time) scale with the hairline. Read Rt as 44 cGyph

on the Rt scale.

Divide the dose rate by 10 since the R1

value was multiplied by 10; then, the dose rate at H + 25

hours is 4.4 cGyph.

ANSWER:

4.4 cGyph.

GIVEN:

R1 = 200 cGyph.

FIND:

Time when Rt = 4 cGyph.

SOLUTION:

Since 4 cGyph cannot be found on the Rt scale, multiply both

Rt and R1 by 10, connect R1 =2,000 cGyph and Rt = 40 cGyph

with the hairline. Read t as H + 27 hours on the time scale.

DO NOT divide the time by 10.

ANSWER:

H + 27 hours.