INTEREST By amount is meant the sum of principal and interest. To find the simple interest on a sum of money, Multiply the principal by the rate to get the interest for 1 year, and this product by the time expressed in years. Example 1. Find the interest and the amount of $1780 for 5 mo. at 7%. Solution: $1780 × .07 × 5 = $51.92, interest for 5 mo. $1780 +$51.92 $1831.92, amount. = A concrete quantity which is contained an exact number of times in another concrete quantity is called an aliquot part of that quantity. Thus, 21 yd. is an aliquot part of 10 yd.; $2.75 is an aliquot part of $11. Example. Find the interest on $780 for 1 yr. 2 mo. 10 da. at 7%. SOLUTION BY ALIQUOT PARTS. 5. $1000 for 1 yr. 3 mo. at 6%; 6. $1200 for 1 yr. 4 mo. at 8%; 7. $1500 for 1 yr. 7 mo. at 9%; 8. $1600 for 2 yr. 3 mo. at 5%; 9. $2000 for 1 yr. 6 mo. at 4%; 10. for 1 yr. 5 mo. at 6%. for 1 yr. 5 mo. at 7%. for 1 yr. 8 mo. at 8%. for 1 yr. 7 mo. at 6%. for 1 yr. 9 mo. at 5 %. $3500 for 10 mo. at 7%; for 7 mo. at 8%. 11. $156.40 for 1 yr. at 41%; at 51%. 12. $185.50 for 1 yr. at 41%; at 7%. 13. $375.60 for 5 mo. at 6%; 14. $928.40 for 2 mo. at 8%; 15. $735.60 for 3 mo. at 7%; 16. 17. for 4 mo. at 5%. for 3 mo. at 6%. for 2 mo. at 8%. $1200 for 2 mo. at 8%; for 5 mo. at 6%. 18. $393.80 for 7 mo. at 4%; for 5 mo. at 3%. for 7 mo. at 6%. for 8 mo. at 9%. 21. $2713.64 for 10 mo. at 9%; for 7 mo. at 8%. 22. $3800 for 11 mo. at 7%; for 10 mo. at 6%. 23. $2825 for 10 mo. at 7%; for 9 mo. at 5%. 24. $2700 for 1 yr. 1 mo. at 6%; for 14 mo. at 5%. for 8 mo. at 4%. 26. $4500 for 8 mo. 15 da. at 6%; for 7 mo. at 7%. 27. $329.50 for 7 mo. 10 da. at 8%. 28. $982 for 9 mo. 18 da. at 6%. 29. $545 for 10 mo. 25 da. at 8%. 30. $775.24 for 11 mo. 24 da. at 7%. L Example. Find the interest on $384.42 from Jan. 11, 1907, to April 30, 1907, at 7%. SOLUTION. First, find the difference between the two 1. $450 from Jan. 12 to April 18 at 6%. 2. $783 from Feb. 14 to April 24 at 8%. 3. $2385 from Mar. 6 to Nov. 11 at 6%. 4. $3950 from July 4 to Dec. 6 at 6%. 5. $4280 from Aug. 31 to Nov. 18 at 8%. 6. $7335 from July 5 to Sept. 14 at 7%. 7. $3280 from Jan. 8 to July 5 at 4%. 8. $4592.40 from Jan. 10 to May 4 at 3%. 9. $384.75 from Mar. 10 to Aug. 14 at 10%. 10. $327.50 from April 6 to July 3 at 9%. 11. $935 from Jan. 1 to April 30 at 41%. 12. $3540 from Jan. 10 to Oct. 5 at 41%. 13. $1382.60 from Feb. 8 to Nov. 1 at 5%. Find the amount of: EXERCISE 85 1. $800 for 1 yr. 2 mo. 15 da. at 4%. HINT. Find the interest and add it to the principal. 2. $580 for 3 yr. 3 mo. at 6%. 3. $750 for 10 mo. 15 da. at 8%. 8. $325 for 9 me. 9. $982 for 8 mo. 16 da. at 5%. 10. $375 for 7 mo. 14 da. at 6%. 11. $1280 from Jan. 10 to July 14 at 8%. 12. $3580 from Jan. 14 to Aug. 18 at 8%. 13. $1500 from March 11 to July 19 at 6%. 14. $4350 from Aug. 14 to Dec. 17 at 7%. 15. $1200 from Jan. 1 to July 8 at 7%. 16. $480 for 9 mo. 15 da. at 5%. 17. $800 for 6 mo. 18 da. at 6%. 18. $550 for 3 mo. 15 da. at 8%. 19. $650 for 5 mo. 12 da. at 6%. 20. $850 for 8 mo. 15 da. at 5%. 21. $980 for 7 mo. at 6%. 22. $2329 for 1 yr. 7 mo. 16 da. at 5%. 23. $3278 for 2 yr. 10 mo. 11 da. at 7%. 24. $2594 for 1 yr. 5 mo. 10 da. at 3%. 25. $978 for 1 yr. 1 mo. 20 da. at 6%. 26. $1857 for 1 yr. 5 mo. 18 da. at 5%. 27. $903.53 for 1 yr. 3 mo. at 5%. MEASUREMENTS SPECIFIC GRAVITY The ratio of the weight of any given volume of a substance to the weight of an equal volume of another substance taken as a standard is called the specific gravity of that substance. The standard taken for solids and liquids is water. Specific gravity, then, simply means how many times as heavy as water a substance is. Thus, cast iron is 7.21 times as heavy as water, and hence its specific gravity is 7.21. Cork is about one fourth as heavy as water, and hence its specific gravity is 1. 1 cu. ft. of water weighs 1,000 oz. 1 Granite. 2.78 Lead. Clay Mercury. 13.57 10.47 Bar iron. 7.79 Platinum 21.5 Example. Find the weight of 28 cu. in. of mercury. SOLUTION. 1728 28 1728 × 1000 oz. = weight of cu. in. of water. × 1000 oz. = weight of 28 cu. in. of water. 13.57 x 28 × 1000 oz. = weight of 28 cu. in. of mercury 432 94990 oz. 219.88 oz. 432 = |