Question

part 2 - arithmetic reasoning
question 13 of 15
the scale drawing diameter of a jet engine fan is 40.6 cm, using a 1 : 5 scale. what is the actual diameter of the fan?
a 203 cm
b 81.2 cm
c 20.3 cm
d 8.12 cm
click the button or type the letter next to your answer.

Explanation:

Step1: Understand the scale

The scale is 1:5, meaning 1 unit on the drawing is 5 units in actual. The drawing diameter is 40.6 cm? Wait, no, wait, maybe the drawing diameter is 40.6? Wait, no, the options are 203, 81.2, 20.3, 8.12. Wait, maybe the drawing diameter is 40.6? Wait, no, let's recheck. Wait, the problem says "the scale drawing diameter of a jet engine fan is 40.6 cm, using a 1:5 scale. What is the actual diameter of the fan?" Wait, no, 1:5 scale means drawing : actual = 1:5. So if drawing is \( d_{drawing} \), actual is \( d_{actual} \), then \( \frac{d_{drawing}}{d_{actual}}=\frac{1}{5} \), so \( d_{actual}=d_{drawing} \times 5 \). Wait, but the options are 203, 81.2, 20.3, 8.12. Wait, maybe the drawing diameter is 40.6? Wait, no, 40.6 5=203? Wait, 40.65=203? 405=200, 0.65=3, so 203. So actual diameter is 40.65=203 cm. Wait, but let's check again. Wait, maybe I got the scale reversed. Wait, 1:5 scale: if the scale is 1:5, that means 1 cm on drawing is 5 cm actual. So drawing diameter is, say, if the actual is x, then drawing is x/5. Wait, the problem says "scale drawing diameter is 40.6 cm, using 1:5 scale". Wait, maybe the drawing is 40.6, and actual is 40.65=203? But 40.65=203, which is option A. Wait, but let's check the options. Option A is 203 cm. So that would be it. Wait, but maybe I misread the drawing diameter. Wait, maybe the drawing diameter is 40.6? Wait, no, maybe the drawing diameter is 40.6? Wait, let's calculate: 40.6 5=203. So actual diameter is 203 cm, which is option A.

Wait, but maybe the drawing diameter is 40.6? Wait, the problem says "the scale drawing diameter of a jet engine fan is 40.6 cm, using a 1:5 scale. What is the actual diameter of the fan?" So scale 1:5 means 1 part drawing = 5 parts actual. So actual = drawing 5. So 40.6 5=203. So answer is A.

Step2: Calculate actual diameter

Given scale 1:5 (drawing : actual), so actual diameter \( d_{actual} = d_{drawing} \times 5 \). If \( d_{drawing} = 40.6 \) cm, then \( d_{actual} = 40.6 \times 5 = 203 \) cm.

Answer:

A. 203 cm